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https://issues.apache.org/jira/browse/POOL-419?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17925267#comment-17925267
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Raju Gupta commented on POOL-419:
---------------------------------
[~ggregory] . Sorry for bothering you. Let me know if you would like to review
this or else I can close the PR. Thanks!
> GenericObjectPoolConfig getNumActive return negative value
> ----------------------------------------------------------
>
> Key: POOL-419
> URL: https://issues.apache.org/jira/browse/POOL-419
> Project: Commons Pool
> Issue Type: Bug
> Affects Versions: 2.12.0
> Reporter: john ms
> Priority: Major
>
> We've notice unexpected counting that is return from getNumActive .
> and it means that allObjects and idleObjects are out of sync.
> Calling returnObject and invalidateObject on the same pooled object from two
> different threads is causing getNumActive to return negative value.
> Why two threads are working on the same object at the same time and the real
> running use case is much complex to described and not relevant, I think.
> Bellow is a simple program to demo the behavior
> {*}Expected result{*}:
> getNumActive=0
>
> {*}Actual result{*}:
> getNumActive=\{negative number}
> If it help debugging the RC, I've notice that returnObject is not
> synchronized over pooled object and verify it's status before using it, like
> it's done in invalidateObject.
> {*}Workaround{*}:
> Synchronize the pooled object before calling returnObject/invalidateObject
>
> Java 17
> {code:java}
> public class PoolObject extends BasePooledObjectFactory<PoolObject> {
> @Override
> public PoolObject create() {
> return new PoolObject();
> }
> @Override
> public PooledObject<PoolObject> wrap(PoolObject poolObject) {
> return new DefaultPooledObject<>(poolObject);
> }
> @Override
> public void passivateObject(PooledObject<PoolObject> pooledObject) {
> }
> }{code}
>
> {code:java}
> public static void main (String [] args) throws Exception {
> ExecutorService executor = Executors.newCachedThreadPool();
> GenericObjectPoolConfig<PoolObject> poolConfig = new
> GenericObjectPoolConfig<>();
> poolConfig.setMaxTotal(200000);
> poolConfig.setMaxIdle(200000);
> poolConfig.setMinIdle(200000);
> ObjectPool<PoolObject> objectPool = new GenericObjectPool<>(new
> PoolObject(), poolConfig);
> for (int i=0; i<1000000; i++){
> PoolObject poolObject= objectPool.borrowObject();
> FutureTask invalidateObject = new FutureTask<>(() -> {
> Thread.sleep(RandomUtils.nextInt(0,10));
> //synchronized (poolObject) { // Workaround bug
> objectPool.invalidateObject(poolObject);
> //}
> return true;
> });
> executor.execute(invalidateObject);
> FutureTask returnObject = new FutureTask<>(() -> {
> Thread.sleep(RandomUtils.nextInt(0,10));
> //synchronized (poolObject) { // Workaround bug
> objectPool.returnObject(poolObject);
> //}
> return true;
> });
> executor.execute(returnObject);
> }
> Thread.sleep(2000);
> executor.shutdown();
> System.out.println("getNumActive=" + objectPool.getNumActive());
> }{code}
>
>
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