[
https://issues.apache.org/jira/browse/POOL-407?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Sarthak Shukla updated POOL-407:
--------------------------------
Description:
While borrowing object from pool, threads are getting stuck. I initialised the
pool size as 1. And had 3 threads created. First thread enters borrowObject
method, since there are no idle objects to poll from, it will create one object
and move forward.
{quote}p = (PooledObject)this.idleObjects.pollFirst();
if (p == null) {
p = this.create();
if (p != null)
Unknown macro: \{ create = true; }
}
{quote}
The other two threads will also follow same path and check for idle
objects(there are none), will try to create one object but the pool size is set
to 1. Thus, the two threads will move forward and enter
*idleObjects.takeFirst()* function. Value of blockWhenExhausted is true and
borrowMaxWaitMillis is -1 as we don't want timeout.
{quote}if (blockWhenExhausted) {
if (p == null) {
if (borrowMaxWaitMillis < 0L) {
p = (PooledObject)this.idleObjects.takeFirst();
} else {
p = (PooledObject)this.idleObjects.pollFirst(borrowMaxWaitMillis,
TimeUnit.MILLISECONDS);
}
}
if (p == null) {
throw new NoSuchElementException("Timeout waiting for idle object");
}
}
{quote}
Now, the main thread does *this.factory.activateObject(p);* and object gets
activated. Now, when the validation is checked *validate =
this.factory.validateObject(p);* it comes out to be false as provider might
have been disconnected.
So, the object is destroyed by calling *this.destroy(p);*
{quote}private void destroy(PooledObject<T> toDestroy) throws Exception {
toDestroy.invalidate();
this.idleObjects.remove(toDestroy);
this.allObjects.remove(new
BaseGenericObjectPool.IdentityWrapper(toDestroy.getObject()));
try {
this.factory.destroyObject(toDestroy);
} finally {
this.destroyedCount.incrementAndGet();
this.createCount.decrementAndGet();
}
}
{quote}
The object which was created is now destroyed and removed from idleObject and
allObjects list. Now, the other two threads are still waiting to take object
from idle objects list but there are no object present. Hence, the two threads
are in wait state for infinite period and the application waits forever until
we kill the process.
{quote}public E takeFirst() throws InterruptedException {
this.lock.lock();
Object var2;
try {
Object x;
while((x = this.unlinkFirst()) == null) {
this.notEmpty.await();
}
var2 = x;
} finally {
this.lock.unlock();
}
return var2;
}
{quote}
was:
While borrowing object from pool, threads are getting stuck. I initialised the
pool size as 1. And had 3 threads created. First thread enters borrowObject
method, since there are no idle objects to poll from, it will create one object
and move forward.
{quote}p = (PooledObject)this.idleObjects.pollFirst();
if (p == null) {
p = this.create();
if (p != null) {
create = true;
}
}
{quote}
The other two threads will also follow same path and check for idle
objects(there are none), will try to create one object but the pool size is set
to 1. Thus, the two threads will move forward and enter
*idleObjects.takeFirst()* function. Value of blockWhenExhausted is true and
borrowMaxWaitMillis is -1 as we don't want timeout.
{quote}if (blockWhenExhausted) {
if (p == null) {
if (borrowMaxWaitMillis < 0L) {
p = (PooledObject)this.idleObjects.takeFirst();
} else {
p = (PooledObject)this.idleObjects.pollFirst(borrowMaxWaitMillis,
TimeUnit.MILLISECONDS);
}
}
if (p == null) {
throw new NoSuchElementException("Timeout waiting for idle object");
}
}
{quote}
Now, the main thread does *this.factory.activateObject(p);* and object gets
activated. Now, when the validation is checked *validate =
this.factory.validateObject(p);* it comes out to be false as provider might
have been disconnected.
So, the object is destroyed by calling *this.destroy(p);*
{quote}private void destroy(PooledObject<T> toDestroy) throws Exception {
toDestroy.invalidate();
this.idleObjects.remove(toDestroy);
this.allObjects.remove(new
BaseGenericObjectPool.IdentityWrapper(toDestroy.getObject()));
try {
this.factory.destroyObject(toDestroy);
} finally {
this.destroyedCount.incrementAndGet();
this.createCount.decrementAndGet();
}
}
{quote}
The object which was created is now destroyed and removed from idleObject and
allObjects list. Now, the other two threads are still waiting to take object
from idle objects list but there are no object present. Hence, the two threads
are in wait state for infinite period and the application waits forever until
we kill the process.
{quote}public E takeFirst() throws InterruptedException {
this.lock.lock();
Object var2;
try {
Object x;
while((x = this.unlinkFirst()) == null) {
this.notEmpty.await();
}
var2 = x;
} finally {
this.lock.unlock();
}
return var2;
}
{quote}
> Threads get stuck when idleObjects list is empty.
> -------------------------------------------------
>
> Key: POOL-407
> URL: https://issues.apache.org/jira/browse/POOL-407
> Project: Commons Pool
> Issue Type: Bug
> Affects Versions: 2.8.1
> Reporter: Sarthak Shukla
> Priority: Major
>
> While borrowing object from pool, threads are getting stuck. I initialised
> the pool size as 1. And had 3 threads created. First thread enters
> borrowObject method, since there are no idle objects to poll from, it will
> create one object and move forward.
> {quote}p = (PooledObject)this.idleObjects.pollFirst();
> if (p == null) {
> p = this.create();
> if (p != null)
> Unknown macro: \{ create = true; }
> }
> {quote}
> The other two threads will also follow same path and check for idle
> objects(there are none), will try to create one object but the pool size is
> set to 1. Thus, the two threads will move forward and enter
> *idleObjects.takeFirst()* function. Value of blockWhenExhausted is true and
> borrowMaxWaitMillis is -1 as we don't want timeout.
> {quote}if (blockWhenExhausted) {
> if (p == null) {
> if (borrowMaxWaitMillis < 0L) {
> p = (PooledObject)this.idleObjects.takeFirst();
> } else {
> p = (PooledObject)this.idleObjects.pollFirst(borrowMaxWaitMillis,
> TimeUnit.MILLISECONDS);
> }
> }
> if (p == null) {
> throw new NoSuchElementException("Timeout waiting for idle object");
> }
> }
> {quote}
> Now, the main thread does *this.factory.activateObject(p);* and object gets
> activated. Now, when the validation is checked *validate =
> this.factory.validateObject(p);* it comes out to be false as provider might
> have been disconnected.
> So, the object is destroyed by calling *this.destroy(p);*
> {quote}private void destroy(PooledObject<T> toDestroy) throws Exception {
> toDestroy.invalidate();
> this.idleObjects.remove(toDestroy);
> this.allObjects.remove(new
> BaseGenericObjectPool.IdentityWrapper(toDestroy.getObject()));
> try {
> this.factory.destroyObject(toDestroy);
> } finally {
> this.destroyedCount.incrementAndGet();
> this.createCount.decrementAndGet();
> }
> }
> {quote}
> The object which was created is now destroyed and removed from idleObject and
> allObjects list. Now, the other two threads are still waiting to take object
> from idle objects list but there are no object present. Hence, the two
> threads are in wait state for infinite period and the application waits
> forever until we kill the process.
> {quote}public E takeFirst() throws InterruptedException {
> this.lock.lock();
> Object var2;
> try {
> Object x;
> while((x = this.unlinkFirst()) == null) {
> this.notEmpty.await();
> }
> var2 = x;
> } finally {
> this.lock.unlock();
> }
> return var2;
> }
> {quote}
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