Hi,
In running some concurrency tests, where multiple threads do simultaneous
puts
against a cache, some of the puts appear to be lost. I run a set of 5 threads
to do
puts, then run a set of five threads to do gets. Many times, all the keys that
are put
into the cache are not present in the cache. I see this with 3.1.0, and also
the newest
stable version, 3.2.1.
Running the contained code produces messages such as:
24 Nov 2009 14:44:50,135 ERROR [] com.m1.test.local.ConcurrencyTest Missing
value for Key1.
The trace shows that the get was done, and that it returned null.
24 Nov 2009 14:44:50,134 TRACE []
org.jboss.cache.interceptors.InvocationContextInterceptor Invoked with command
GetKeyValueCommand{fqn=/BigNode, key=Key1, sendNodeEvent=true} and
InvocationContext [InvocationContext{transaction=null, globalTransaction=null,
transactionContext=null, optionOverrides=Option{failSilently=false,
cacheModeLocal=false, dataVersion=null, suppressLocking=false,
lockAcquisitionTimeout=-1, forceDataGravitation=false,
skipDataGravitation=false, forceAsynchronous=false, forceSynchronous=false,
suppressPersistence=false, suppressEventNotification=false}, originLocal=true,
bypassUnmarshalling=false}]
24 Nov 2009 14:44:50,134 TRACE [] org.jboss.cache.interceptors.CallInterceptor
Executing command: GetKeyValueCommand{fqn=/BigNode, key=Key1,
sendNodeEvent=true}.
24 Nov 2009 14:44:50,134 TRACE []
org.jboss.cache.commands.read.GetKeyValueCommand Found value null
However, earlier in the run I have put the Key into the cache.
24 Nov 2009 14:44:40,831 INFO [] com.m1.test.local.ConcurrencyTest Putting
Key1
And the trace indicates that a value was put for the key:
24 Nov 2009 14:44:40,829 TRACE []
org.jboss.cache.interceptors.InvocationContextInterceptor Invoked with command
PutKeyValueCommand{fqn=/BigNode, dataVersion=null, globalTransaction=null,
key=Key1, value=This is a test.} and InvocationContext
[InvocationContext{transaction=null, globalTransaction=null,
transactionContext=null, optionOverrides=Option{failSilently=false,
cacheModeLocal=false, dataVersion=null, suppressLocking=false,
lockAcquisitionTimeout=-1, forceDataGravitation=false,
skipDataGravitation=false, forceAsynchronous=false, forceSynchronous=false,
suppressPersistence=false, suppressEventNotification=false}, originLocal=true,
bypassUnmarshalling=false}]
These log records are all for the same run of the test code. Since the get
happens after the put, I would expect for the corresponding value to be
returned.
I have appended the test, which is a reasonably simple and self contained
case.
Is there anything else, perhaps in terms of MVCC options I should try?
Thanks,
Alex
| package com.m1.test.local;
|
| import org.jboss.cache.Cache;
| import org.jboss.cache.config.Configuration;
| import java.util.concurrent.CyclicBarrier;
| import org.jboss.cache.DefaultCacheFactory;
| import org.jboss.cache.Fqn;
| import java.util.HashSet;
| import org.apache.commons.logging.Log;
| import org.apache.commons.logging.LogFactory;
|
| /**
| * This test will be used to put a specific number of enteries into the
cache,
| * and measure the amount of memory taken by the cache.
| */
| public class ConcurrencyTest
| {
| private static final Fqn<String> FQN =
Fqn.fromString("BigNode");
| private static final Log LOG =
LogFactory.getLog(ConcurrencyTest.class);
| private static final int NTHREADS = 5;
| private static final String VALUE = "This is a test.";
|
| private final CyclicBarrier barrier = new CyclicBarrier(NTHREADS);
| private Thread[] threads = new Thread[NTHREADS];
|
|
| public ConcurrencyTest()
| throws Throwable
| {
| Cache<Object, Object> cache = createCache();
|
| for (int iteration=0; iteration<10; iteration++)
| {
| for(int j=0; j<NTHREADS; j++)
| {
| threads[j] = new WriteThread(cache, barrier, iteration, j);
| threads[j].start();
| }
|
| for(int j=0; j<NTHREADS; j++)
| {
| threads[j].join(500);
| }
| }
|
| for (int iteration=0; iteration<10; iteration++)
| {
| for(int j=0; j<NTHREADS; j++)
| {
| threads[j] = new ReadThread(cache, barrier, iteration, j);
| threads[j].start();
| }
|
| for(int j=0; j<NTHREADS; j++)
| {
| threads[j].join(500);
| }
| }
|
| while(true)
| {
| Thread.sleep(3600000);
| }
| }
|
| public Cache<Object, Object> createCache()
| throws Exception
| {
| Cache<Object, Object> cache = new
DefaultCacheFactory().createCache();
| cache.create();
| cache.start();
| return cache;
| }
|
| private static class WriteThread extends Thread
| {
| private CyclicBarrier barrier;
| private Cache<Object, Object> cache;
| private int iteration;
| private int writer;
|
| public WriteThread(Cache<Object, Object> cache, CyclicBarrier
barrier,
| int iteration, int
writer)
| throws Throwable
| {
| this.cache = cache;
| this.barrier = barrier;
| this.iteration = iteration;
| this.writer = writer;
| }
|
| /**
| * Run a common set of tests in each thread.
| */
| public void run()
| {
| try
| {
| barrier.await();
|
| for (int id=1000*iteration + 100*writer; id<1000*iteration +
100*(writer+1); id++)
| {
| String key = "Key" + id;
| cache.put(FQN, key, VALUE);
| LOG.info("Putting " + key);
| }
| }
| catch (Exception exception)
| {
| LOG.error("Write thread failed.", exception);
| }
| }
| }
|
|
| private static class ReadThread extends Thread
| {
| private CyclicBarrier barrier;
| private Cache<Object, Object> cache;
| private int iteration;
| private int writer;
|
| public ReadThread(Cache<Object, Object> cache, CyclicBarrier
barrier,
| int iteration, int
writer)
| throws Throwable
| {
| this.cache = cache;
| this.barrier = barrier;
| this.iteration = iteration;
| this.writer = writer;
| }
|
| /**
| * Run a common set of tests in each thread.
| */
| public void run()
| {
| try
| {
| barrier.await();
|
| for (int id=1000*iteration + 100*writer; id<1000*iteration +
100*(writer+1); id++)
| {
| String key = "Key" + id;
| Object result = cache.get(FQN, key);
| if (result == null)
| {
| LOG.error("Missing value for " + key + ".");
| }
| }
| }
| catch (Exception exception)
| {
| LOG.error("ReadThread failed.", exception);
| }
| }
| }
|
| public static void main(String[] args)
| throws Throwable
| {
| ConcurrencyTest test = new ConcurrencyTest();
| }
| }
|
Some other details:
$ java -version
java version "1.6.0_16"
Java(TM) SE Runtime Environment (build 1.6.0_16-b01)
Java HotSpot(TM) 64-Bit Server VM (build 14.2-b01, mixed mode)
$ uname -a
Linux aklugelnx 2.6.28-16-generic #55-Ubuntu SMP Tue Oct 20 19:48:32 UTC 2009
x86_64 GNU/Linux
The only JVM option I use is -Xmx2g to ensure enough space in the cache.
I would welcome suggestions, and even requests for more details or some
additional tests to further pin down why I don see what I expect. I be happy to
find it to be a configuration option I missed.
Thanks,
Alex
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