Here is a Dzone article we published 0n 2017-5-14.
The Java 8 streams feature is an excellent way to perform semi-declarative operations on Maps, especially as it provides improved performance via almost free parallelism, taking advantage of the increasing core count of modern computers. However, the parallelism is primarily useful in single-threaded applications which have batch operations to do on Maps. Servers that are under continuous load react in a completely different way to parallelism, and we will show here graphically what happens.
We will discuss:
- The most basic stream operations and how to use them, as applied to a max() function. This function is very fast on Long-valued Maps, so the differences between Map implementations is most apparent;
- The effects of heavy server load on stream performance, with graphic results;
- The Java Microbenchmarking Harness JMH, with the example code which generated the results, and;
- The streaming performance of AirConcurrentMap, a standard ConcurrentNavigableMap written by the author.
Basic Stream Use
It is easy to use a stream to calculate, for example, the maximum of a Long-valued Map, which will be our test case. We can do it several ways. As an example, we can use a reduce():
Map<Object, Long> map = new HashMap<Object, Long>(); //… return map.values().stream() .reduce(Long.MIN_VALUE, (x, y) -> x > y ? x : y);
In order to maximize performance, we can convert the stream to a LongStream:
return map.values().stream() .mapToLong(o -> ((Long)o).longValue()) .reduce(Long.MIN_VALUE, (x, y) -> x > y ? x : y);
Then, in order to get the parallelism for free, we just chain in a .parallel() invocation:
return map.values().stream().parallel() .mapToLong(o -> ((Long)o).longValue()) .reduce(Long.MIN_VALUE, (x, y) -> x > y ? x : y);
It turns out the LongStream has a built-in max() method, but it returns an OptionalLong, which is a bit more trouble so we ignore it. It just does a reduce(Math::max) anyway.
Test Setup
We used the excellent Java Microbenchmarking Harness to do fair and precise testing. This framework handles almost all of the hard work in testing, including process forking, setup, threading, looping, timing, parameterization, and statistics. It is good for small pieces of code that are to execute frequently as well as slower operations. We present the entire test code below. Our test code also has a selection of other interesting Map performance measurements. The scanning techniques we cover are very important, because they can easily become the chief bottleneck, and not all situations cause get(), put(), and remove() to be limiting, particularly in large Maps.
We will cover various techniques for finding the maximum of a Map with Long values, including iterating, forEach(), serial streams, and parallel streams, for both 8- and 100-thread loads. The system is an Intel X86-64 2.4GHz quad core. So, with 8 threads we are fully loading the CPU, but many servers have very large numbers of threads handling web hits.
We use only ConcurrentMaps
In this testing, we assume that the Maps may be modified during the scanning. This will normally be the case in a server environment, because most Maps cannot simply be loaded with data when the server boots and then held static thereafter. Various tricks can be used to avoid problems with write/write and read/write access overlap, but in general, if a system contains multiple threads, non-concurrent Maps can be very dangerous. Access overlaps may easily return wrong results or even corrupt the structure of the Map, and failures may manifest rarely and may be difficult to understand, detect and diagnose. So, we do not use bare HashMap and TreeMap, but wrap them using Collections.synchronizedMap(). Catching ConcurrentModificationException is not a reliable means to detect wrong results or corruption and it is not guaranteed to be thrown at all, in spite of the choice of a particular Map implementation to have the ‘fail-fast’ characteristic.
Problems with Collections.synchronizedMap()
It is easy to adapt HashMap and TreeMap – or any other Map – for Thread safety using Collections.synchronizedMap(Map). This static method simply wraps and returns the given Map in a new instance of a private SynchronizedMap which delegates within a synchronized() block. However, the resulting Map is not very satisfactory. The model is incomplete, slow, and risky:
- The wrapped Map may no longer be used directly, so all references to it must be hidden safely;
- Iterators, forEach(), Spliterators, and streams uses are not synchronized (possibly others too?). These must be synchronized explicitly at the point of use. The synchronization must be on the SynchronizedMap itself, and not on the wrapped Map. Outside code that receives a SynchronizedMap may fail to do such scan synchronization;
- All access is serialized, so only one core is used;
- Scans may dramatically delay otherwise fast operations such as get(), put() and remove() in other Threads, reducing throughput in those Threads: ConcurrentMaps avoid this problem;
- If a Map is wrapped more than once in different places, access may still overlap and cause problems. It is not enough to do a temporary wrapping at each point of use;
- Synchronization is slow compared to some Map operations, especially when wait queues build up. Synchronization is very fast, however, when there is no contention.
Nevertheless, we test HashMap and TreeMap in their synchronized forms.
The Tested Maps
We test over:
- AirConcurrentMap – a util.concurrent.ConcurrentNavigableMap from boilerbay.com,
- Synchronized java.util.HashMap,
- Sychronized java.util.TreeMap,
- util.concurrent.ConcurrentHashMap, and
- util.concurrent.ConcurrentSkipListMap.
General Conclusions
These are rough observations – you should look at the graphs for yourself. Generally, the four scanning techniques have widely different startup times, efficiency, and inter-thread interference. The variations over different Map implementations are extreme as well.
- Iteration is slower than Map.forEach(BiConsumer), sometimes very much;
- Iteration and forEach() start fast, peak at about 100 entries, then slow down;
- Streams have a significant startup delay for Maps of only a few entries;
- The synchronized HashMap and TreeMap are very slow;
- The 8-Thread case is comparable to the 100-Thread case.
- For small Maps, ConcurrentSkipListMap is best, for large Maps, AirConcurrentMap is best, with a break-even point from 100 to 10K Entries.
- Parallel streams are slow, and actually slower than serial streams in these high-load cases, except for AirConcurrentMap, which remains fast. This is because AirConcurrentMap 3.2 uses only serial scan even for parallel streams.
The Graphs
The Java Microbenchmarking Harness Code
The JMH code is very concise owing to the fact that only a few Annotated features are needed, factoring out almost everything but the state, setup methods, and benchmark methods. We have parameterized the tests so that JMH will sweep over a range of Map sizes and Map implementations. The testing uses the Maven framework so it is easy to setup and use. The code here tests many interesting performance features. The command line can override the setup defaults. Each benchmark method must return a value so that there is some tangible result that prevents the JIT from removing all the code!
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Threads;
import org.openjdk.jmh.annotations.Warmup;
@Fork(1)
@Warmup(iterations = 2, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 2, time = 1, timeUnit = TimeUnit.SECONDS)
@BenchmarkMode(Mode.Throughput)
// @OutputTimeUnit(TimeUnit.SECONDS)
@Threads(8)
@State(Scope.Benchmark)
public class ServerLoadJMHMapTest {
@Param({ "0", "1", "10", "100", "1000", "10000", "100000", "1000000", "10000000" })
static long mapSize;
@Param({
"com.infinitydb.map.air.AirConcurrentMap",
// "java.util.HashMap",
// "java.util.TreeMap",
"java.util.concurrent.ConcurrentHashMap",
"java.util.concurrent.ConcurrentSkipListMap"
})
static String mapClassName;
static Map<Long, Long> map;
// This will be optimized out by the JIT
static boolean isCollectionsSynchronizedMap;
@Setup(Level.Trial)
static public void setup() throws InstantiationException, IllegalAccessException, ClassNotFoundException {
Class<Map<Long, Long>> mapClass =
(Class<Map<Long, Long>>)Class.forName(mapClassName);
map = mapClass.newInstance();
if (!(map instanceof ConcurrentMap)) {
isCollectionsSynchronizedMap = true;
if (!(map instanceof NavigableMap))
map = Collections.synchronizedMap(map);
else
map = Collections.synchronizedNavigableMap((NavigableMap)map);
}
// Random random = new Random(System.nanoTime());
Random random = new Random(1);
// Load up the Map
for (long i = 0; i < mapSize; i++) {
long o = random.nextLong();
map.put(o, o);
}
}
@Benchmark
public static long testServerLoadGet() {
long k = ThreadLocalRandom.current().nextLong();
Long v = map.get(k);
return v == null ? Integer.MIN_VALUE : v;
}
/*
* We have to do both put() and remove() so the map doesn't change size and
* so the remove() actually has an effect because the removed key actually
* exists.
*/
@Benchmark
public static long testServerLoadPutRemove() {
long k = ThreadLocalRandom.current().nextLong();;
map.put(k, k);
return map.remove(k);
}
@Benchmark
public static long testServerLoadIterator() {
long max = Long.MIN_VALUE;
// This if condition is actually very fast and the JIT will remove it.
if (isCollectionsSynchronizedMap) {
// Must synch on the map, not the iterator or values!
// This prevents concurrent modification
synchronized (map) {
for (Long v : map.values()) {
max = v > max ? v : max;
}
}
} else {
for (Long v : map.values()) {
max = v > max ? v : max;
}
}
return max;
}
@Benchmark
public static long testServerLoadForEach() {
class SummingBiConsumer implements BiConsumer<Object, Long> {
long max = Long.MIN_VALUE;
public void accept(Object k, Long v) {
max = v > max ? v : max;
}
}
SummingBiConsumer summingBiConsumer = new SummingBiConsumer();
if (isCollectionsSynchronizedMap) {
// Must synch on the map, not the iterator or values!
// This prevents concurrent modification
synchronized (map) {
map.forEach(summingBiConsumer);
}
} else {
map.forEach(summingBiConsumer);
}
return summingBiConsumer.max;
}
@Benchmark
public static long testServerLoadSerialStream() {
// This if condition is actually very fast and the JIT will remove it.
if (isCollectionsSynchronizedMap) {
// Must synch on the map, not the iterator or values!
// This prevents concurrent modification
synchronized (map) {
return map.values().stream()
.mapToLong(o -> ((Long)o).longValue())
.reduce(Long.MIN_VALUE, (x, y) -> x > y ? x : y);
}
} else {
return map.values().stream()
.mapToLong(o -> ((Long)o).longValue())
.reduce(Long.MIN_VALUE, (x, y) -> x > y ? x : y);
}
}
@Benchmark
public static long testServerLoadParallelStream() {
// This if condition is actually very fast and the JIT will remove it.
if (isCollectionsSynchronizedMap) {
// Must synch on the map, not the iterator or set!
// This prevents concurrent modification
synchronized (map) {
return map.values().stream().parallel()
.mapToLong(o -> ((Long)o).longValue())
.reduce(Long.MIN_VALUE, (x, y) -> x > y ? x : y);
}
} else {
return map.values().stream().parallel()
.mapToLong(o -> ((Long)o).longValue())
.reduce(Long.MIN_VALUE, (x, y) -> x > y ? x : y);
}
}
}
Result Data
Here is the result data obtained by running this command with a 64-bit JVM:
java -Xmx4g -jar target/benchmarks.jar
Note that the graphical representations show performance in terms of Values per second, which is the product of ops/s and mapsize. As a bonus, the performance of get() is included, plus that of put() combined with remove().
# Run complete. Total time: 00:53:49 Benchmark (mapClassName) (mapSize) Mode Cnt Score Error Units ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 0 thrpt 2 23047433.238 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 1 thrpt 2 20491184.297 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 10 thrpt 2 11020398.731 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 100 thrpt 2 4558195.217 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 1000 thrpt 2 1712967.071 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 10000 thrpt 2 171565.943 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 100000 thrpt 2 18723.255 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 1000000 thrpt 2 739.927 ops/s ServerLoadJMHMapTest.testServerLoadForEach com.infinitydb.map.air.AirConcurrentMap 10000000 thrpt 2 53.046 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 0 thrpt 2 17036848.467 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 1 thrpt 2 14748081.919 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 10 thrpt 2 10329174.206 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 100 thrpt 2 2700102.001 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 1000 thrpt 2 317592.584 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 10000 thrpt 2 7593.322 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 100000 thrpt 2 1750.220 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 1000000 thrpt 2 125.705 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.HashMap 10000000 thrpt 2 11.524 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 0 thrpt 2 18178273.043 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 1 thrpt 2 18544975.851 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 10 thrpt 2 9115543.859 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 100 thrpt 2 1829794.525 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 1000 thrpt 2 142824.981 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 10000 thrpt 2 8600.766 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 100000 thrpt 2 381.963 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 1000000 thrpt 2 46.626 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.TreeMap 10000000 thrpt 2 6.144 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 0 thrpt 2 1178182652.402 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 1 thrpt 2 152602535.950 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 10 thrpt 2 79011494.041 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 100 thrpt 2 6656813.612 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 1000 thrpt 2 723730.510 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 10000 thrpt 2 34412.013 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 100000 thrpt 2 934.148 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 1000000 thrpt 2 84.053 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentHashMap 10000000 thrpt 2 8.387 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 0 thrpt 2 1075001021.052 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 1 thrpt 2 634515157.695 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 10 thrpt 2 164781749.555 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 100 thrpt 2 20618465.193 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 1000 thrpt 2 1401510.997 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 10000 thrpt 2 51707.682 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 100000 thrpt 2 1213.355 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 1000000 thrpt 2 121.542 ops/s ServerLoadJMHMapTest.testServerLoadForEach java.util.concurrent.ConcurrentSkipListMap 10000000 thrpt 2 8.082 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 0 thrpt 2 5789752.082 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 1 thrpt 2 7916730.951 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 10 thrpt 2 5945631.282 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 100 thrpt 2 4517997.389 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 1000 thrpt 2 3604161.595 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 10000 thrpt 2 4310142.861 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 100000 thrpt 2 4678352.906 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 1000000 thrpt 2 5297491.406 ops/s ServerLoadJMHMapTest.testServerLoadGet com.infinitydb.map.air.AirConcurrentMap 10000000 thrpt 2 2875975.481 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 0 thrpt 2 8112338.901 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 1 thrpt 2 8407822.931 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 10 thrpt 2 7650281.880 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 100 thrpt 2 8194484.303 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 1000 thrpt 2 7314026.839 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 10000 thrpt 2 7758733.115 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 100000 thrpt 2 6264293.372 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 1000000 thrpt 2 3694720.332 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.HashMap 10000000 thrpt 2 616921.335 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 0 thrpt 2 8904266.711 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 1 thrpt 2 8714794.742 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 10 thrpt 2 8147617.952 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 100 thrpt 2 6222054.495 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 1000 thrpt 2 3594163.202 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 10000 thrpt 2 3013752.755 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 100000 thrpt 2 1618463.932 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 1000000 thrpt 2 838131.382 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.TreeMap 10000000 thrpt 2 609922.560 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 0 thrpt 2 3111304.489 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 1 thrpt 2 3102437.302 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 10 thrpt 2 3094475.655 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 100 thrpt 2 3100185.812 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 1000 thrpt 2 3189228.398 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 10000 thrpt 2 3169807.105 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 100000 thrpt 2 3097192.146 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 1000000 thrpt 2 3100381.782 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentHashMap 10000000 thrpt 2 1898969.068 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 0 thrpt 2 3457006.498 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 1 thrpt 2 3133892.724 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 10 thrpt 2 3117124.456 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 100 thrpt 2 3340889.066 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 1000 thrpt 2 3417555.903 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 10000 thrpt 2 4016906.843 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 100000 thrpt 2 5530252.120 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 1000000 thrpt 2 3796383.168 ops/s ServerLoadJMHMapTest.testServerLoadGet java.util.concurrent.ConcurrentSkipListMap 10000000 thrpt 2 1263945.390 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 0 thrpt 2 28014823.979 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 1 thrpt 2 24048597.060 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 10 thrpt 2 11126146.184 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 100 thrpt 2 4435674.947 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 1000 thrpt 2 103464.889 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 10000 thrpt 2 50524.608 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 100000 thrpt 2 4736.649 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 1000000 thrpt 2 301.904 ops/s ServerLoadJMHMapTest.testServerLoadIterator com.infinitydb.map.air.AirConcurrentMap 10000000 thrpt 2 14.594 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 0 thrpt 2 6270544.346 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 1 thrpt 2 6406216.460 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 10 thrpt 2 6044084.811 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 100 thrpt 2 2026376.771 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 1000 thrpt 2 199345.652 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 10000 thrpt 2 9647.064 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 100000 thrpt 2 1362.145 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 1000000 thrpt 2 155.430 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.HashMap 10000000 thrpt 2 17.683 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 0 thrpt 2 6225070.005 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 1 thrpt 2 5917760.935 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 10 thrpt 2 5838389.725 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 100 thrpt 2 1728546.641 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 1000 thrpt 2 142588.839 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 10000 thrpt 2 4730.083 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 100000 thrpt 2 878.238 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 1000000 thrpt 2 67.434 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.TreeMap 10000000 thrpt 2 6.502 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 0 thrpt 2 860000338.409 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 1 thrpt 2 154597815.396 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 10 thrpt 2 81745604.372 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 100 thrpt 2 7093417.135 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 1000 thrpt 2 668463.955 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 10000 thrpt 2 30176.666 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 100000 thrpt 2 928.106 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 1000000 thrpt 2 74.003 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentHashMap 10000000 thrpt 2 8.559 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 0 thrpt 2 684741984.183 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 1 thrpt 2 506261119.993 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 10 thrpt 2 147373264.854 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 100 thrpt 2 18999835.182 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 1000 thrpt 2 1527160.431 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 10000 thrpt 2 53445.149 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 100000 thrpt 2 1427.061 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 1000000 thrpt 2 147.546 ops/s ServerLoadJMHMapTest.testServerLoadIterator java.util.concurrent.ConcurrentSkipListMap 10000000 thrpt 2 8.782 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 0 thrpt 2 6777906.317 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 1 thrpt 2 6653033.426 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 10 thrpt 2 5274794.953 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 100 thrpt 2 3300112.876 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 1000 thrpt 2 1722115.468 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 10000 thrpt 2 171773.428 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 100000 thrpt 2 19295.182 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 1000000 thrpt 2 723.960 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream com.infinitydb.map.air.AirConcurrentMap 10000000 thrpt 2 47.434 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 0 thrpt 2 4158483.876 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 1 thrpt 2 3714731.001 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 10 thrpt 2 171207.735 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 100 thrpt 2 84009.851 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 1000 thrpt 2 66503.603 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 10000 thrpt 2 18284.734 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 100000 thrpt 2 694.486 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 1000000 thrpt 2 62.325 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.HashMap 10000000 thrpt 2 8.474 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 0 thrpt 2 3981301.448 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 1 thrpt 2 3988870.306 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 10 thrpt 2 155345.974 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 100 thrpt 2 97388.076 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 1000 thrpt 2 63098.729 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 10000 thrpt 2 20633.695 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 100000 thrpt 2 1642.898 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 1000000 thrpt 2 67.075 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.TreeMap 10000000 thrpt 2 8.622 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 0 thrpt 2 23130698.292 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 1 thrpt 2 22213585.616 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 10 thrpt 2 2055151.185 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 100 thrpt 2 646402.804 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 1000 thrpt 2 268935.434 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 10000 thrpt 2 28443.726 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 100000 thrpt 2 1670.126 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 1000000 thrpt 2 57.028 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentHashMap 10000000 thrpt 2 7.111 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 0 thrpt 2 27538202.864 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 1 thrpt 2 27337394.527 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 10 thrpt 2 4350052.833 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 100 thrpt 2 690071.500 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 1000 thrpt 2 117743.840 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 10000 thrpt 2 24077.926 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 100000 thrpt 2 3257.692 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 1000000 thrpt 2 178.520 ops/s ServerLoadJMHMapTest.testServerLoadParallelStream java.util.concurrent.ConcurrentSkipListMap 10000000 thrpt 2 7.285 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 0 thrpt 2 2645942.975 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 1 thrpt 2 2655891.644 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 10 thrpt 2 2610152.221 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 100 thrpt 2 2584800.401 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 1000 thrpt 2 2543944.483 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 10000 thrpt 2 974393.128 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 100000 thrpt 2 2651240.002 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 1000000 thrpt 2 4002925.744 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove com.infinitydb.map.air.AirConcurrentMap 10000000 thrpt 2 1445806.741 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 0 thrpt 2 3482365.861 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 1 thrpt 2 3703935.246 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 10 thrpt 2 3727039.603 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 100 thrpt 2 3558929.641 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 1000 thrpt 2 3246673.701 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 10000 thrpt 2 3220283.326 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 100000 thrpt 2 3132581.289 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 1000000 thrpt 2 2456302.191 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.HashMap 10000000 thrpt 2 1335042.831 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 0 thrpt 2 3028583.757 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 1 thrpt 2 3707695.065 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 10 thrpt 2 3460363.938 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 100 thrpt 2 2838226.314 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 1000 thrpt 2 3001686.525 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 10000 thrpt 2 2473986.854 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 100000 thrpt 2 2199882.581 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 1000000 thrpt 2 1183774.194 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.TreeMap 10000000 thrpt 2 293745.620 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 0 thrpt 2 3496060.019 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 1 thrpt 2 3552443.412 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 10 thrpt 2 3601286.144 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 100 thrpt 2 3523514.309 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 1000 thrpt 2 3448373.725 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 10000 thrpt 2 3484472.261 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 100000 thrpt 2 3433852.622 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 1000000 thrpt 2 3602261.470 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentHashMap 10000000 thrpt 2 945151.433 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 0 thrpt 2 2873985.824 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 1 thrpt 2 3055640.162 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 10 thrpt 2 2932301.437 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 100 thrpt 2 4911826.805 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 1000 thrpt 2 5117860.885 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 10000 thrpt 2 5146802.901 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 100000 thrpt 2 5835795.891 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 1000000 thrpt 2 3208159.162 ops/s ServerLoadJMHMapTest.testServerLoadPutRemove java.util.concurrent.ConcurrentSkipListMap 10000000 thrpt 2 413309.235 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 0 thrpt 2 10335910.649 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 1 thrpt 2 9328192.407 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 10 thrpt 2 4868566.851 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 100 thrpt 2 3658623.399 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 1000 thrpt 2 1642789.440 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 10000 thrpt 2 174199.022 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 100000 thrpt 2 18281.599 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 1000000 thrpt 2 827.833 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream com.infinitydb.map.air.AirConcurrentMap 10000000 thrpt 2 52.652 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 0 thrpt 2 5145836.764 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 1 thrpt 2 4224648.552 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 10 thrpt 2 3875736.974 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 100 thrpt 2 992210.569 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 1000 thrpt 2 80769.068 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 10000 thrpt 2 7358.194 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 100000 thrpt 2 462.946 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 1000000 thrpt 2 97.642 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.HashMap 10000000 thrpt 2 13.733 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 0 thrpt 2 5603446.680 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 1 thrpt 2 4708457.280 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 10 thrpt 2 4154241.202 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 100 thrpt 2 1383738.489 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 1000 thrpt 2 150193.167 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 10000 thrpt 2 8537.591 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 100000 thrpt 2 557.913 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 1000000 thrpt 2 104.055 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.TreeMap 10000000 thrpt 2 9.081 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 0 thrpt 2 34912231.548 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 1 thrpt 2 34844548.692 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 10 thrpt 2 30093686.483 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 100 thrpt 2 3602677.843 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 1000 thrpt 2 470995.908 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 10000 thrpt 2 28279.414 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 100000 thrpt 2 908.598 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 1000000 thrpt 2 71.442 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentHashMap 10000000 thrpt 2 7.822 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 0 thrpt 2 39319374.682 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 1 thrpt 2 34374487.204 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 10 thrpt 2 33398466.884 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 100 thrpt 2 5898985.205 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 1000 thrpt 2 1185387.269 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 10000 thrpt 2 100570.817 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 100000 thrpt 2 1420.870 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 1000000 thrpt 2 125.789 ops/s ServerLoadJMHMapTest.testServerLoadSerialStream java.util.concurrent.ConcurrentSkipListMap 10000000 thrpt 2 9.130 ops/s
Summary
Under heavy thread load, parallel systems behave differently than in the few-threaded case. Parallelism only works well when cores are actually available for use that would otherwise be idle. The overhead of the parallelism framework can become very great. Collections.synchronizedMap() is slow, inconvenient and risky