Because the "cancelTimer" defined in Driver.java.in is different from
the "cancelTimer" defined in AbstractJdbc2Statement.java. The first one
is declared by
"java.util.Timer",the second is declared by "java.util.TimerTask".Only
the Timer class has purge function ,and TimerTask not.
On 02/18/2014 08:00 PM, Dave Cramer wrote:
> Why would you not just call purge on the cancelTimer ?
>
> Dave Cramer
>
> dave.cramer(at)credativ(dot)ca
> http://www.credativ.ca
>
>
> On Tue, Feb 18, 2014 at 3:30 AM, zhangyuanchao
> <zhangyuanchao(at)highgo(dot)com(dot)cn <mailto:zhangyuanchao(at)highgo(dot)com(dot)cn>> wrote:
>
> On 02/17/2014 09:08 PM, Dave Cramer wrote:
>> Hi,
>>
>> There were some fixes put into the latest version can you check
>> out the snapshot here ?
>>
>> https://oss.sonatype.org/content/repositories/snapshots/org/postgresql/postgresql/
>>
>> Dave Cramer
>>
>> dave.cramer(at)credativ(dot)ca
>> http://www.credativ.ca
>>
>>
>> On Tue, Feb 11, 2014 at 2:01 AM, zhangyuanchao
>> <zhangyuanchao(at)highgo(dot)com(dot)cn
>> <mailto:zhangyuanchao(at)highgo(dot)com(dot)cn>> wrote:
>>
>> On 02/10/2014 07:18 PM, Dave Cramer wrote:
>>> I think this is a known issues. What version of the driver
>>> are you using ?
>>>
>>> Dave Cramer
>>>
>>> dave.cramer(at)credativ(dot)ca
>>> http://www.credativ.ca
>>>
>>>
>>> On Sun, Feb 9, 2014 at 10:46 PM, zhangyuanchao
>>> <zhangyuanchao(at)highgo(dot)com(dot)cn
>>> <mailto:zhangyuanchao(at)highgo(dot)com(dot)cn>> wrote:
>>>
>>> Hi,
>>> I have a question about setting query timeout by jdbc.
>>> When tested my application with Tomcat7.0 and
>>> loadrunner,my tomcat's configure file is like this:
>>> <Resource ......
>>> jdbcInterceptors="QueryTimeoutInterceptor(queryTimeout=600)"
>>> ....../>.
>>> After setting like above ,tomcat will call the jdbc's
>>> setQueryTimeout function and set the query timeout to
>>> 600seconds for each statement.
>>> Next,i start my test with 150 concurrency.After about 10
>>> minutes later,i found the response time was much longer
>>> than before.At that moment,i found there were a lot of
>>> statement object in the heap memory of the JVM.And the
>>> JVM's gc could not clean these objects,because they were
>>> referenced by the TimerTask.So i read the source code of
>>> the jdbc and Timer class,i found the mainloop function
>>> of the Timer calss can cause the problem.This is the
>>> code of mainloop function in Timer class and i think the
>>> red colour text is that what cause the problem:
>>>
>>> private void mainLoop() {
>>> while (true) {
>>> try {
>>> TimerTask task;
>>> boolean taskFired;
>>> synchronized(queue) {
>>> // Wait for queue to become non-empty
>>> while (queue.isEmpty() && newTasksMayBeScheduled)
>>> queue.wait();
>>> if (queue.isEmpty())
>>> break; // Queue is empty and will forever remain; die
>>>
>>> // Queue nonempty; look at first evt and do the right thing
>>> long currentTime, executionTime;
>>> task = queue.getMin();fixes
>>>
>>> synchronized(task.lock) {
>>> if (task.state == TimerTask.CANCELLED) {
>>> queue.removeMin();
>>> continue; // No action required, poll queue again
>>> }
>>> currentTime = System.currentTimeMillis();
>>> executionTime = task.nextExecutionTime;
>>> if (taskFired = (executionTime<=currentTime)) {
>>> if (task.period == 0) { // Non-repeating, remove
>>> queue.removeMin();
>>> task.state = TimerTask.EXECUTED;
>>> } else { // Repeating task, reschedule
>>> queue.rescheduleMin(
>>> task.period<0 ? currentTime - task.period
>>> : executionTime + task.period);
>>> }
>>> }
>>> }
>>> if (!taskFired) // Task hasn't yet fired; wait
>>> queue.wait(executionTime - currentTime);
>>> }
>>> if (taskFired) // Task fired; run it, holding no locks
>>> task.run();
>>> } catch(InterruptedException e) {
>>> }
>>> }
>>> }
>>> }
>>> So,i want to ask if there is any solution for this problem.
>>> Thanks very much.
>>>
>>>
>>>
>> Hi Dave,
>> Thanks for your response.
>> The version of driver that i am using is 9.3-1100(the latest
>> version).And i searched some similar problem in the mail
>> list,but i did not get it.I think the reason is : when an
>> statement has been execute finished successfully and the
>> statement cancel the timertask,but the timertask is still in
>> Timer's queue.So the statement is always referenced by the
>> Timer class and it can not be cleaned.
>> Let me look at the mainloop function of Timer class.The part
>> that is marked red colour can cause the mainloop stop,so the
>> canceled timetask can not be removed from the queue.If i set
>> the query timeout to 600 seconds,the mainloop will wait for
>> about ten minutes.In the ten minutes,there will be more an
>> more statement in the JVM heap.
>> I think this is what cause the problem,but i don't have some
>> good idea to solve it.Do you have some solution?Thanks a lot.
>>
>>
> Hi,
> I checked out the snapshot you sent to me.And i download this
> https://oss.sonatype.org/content/repositories/snapshots/org/postgresql/postgresql/9.3-1101-jdbc4-SNAPSHOT/postgresql-9.3-1101-jdbc4-20140214.105528-4.jar
> and test my application , i got the same problem.I look at the
> fixes that was put into the latest version,i think that can not
> solve my issue.I think you may not understand my question.
> I have a solution like this,
> adding a function into Driver.java.in <http://Driver.java.in>:
> public static Timer getCancelTimer()
> {
> return cancelTimer;
> }
> and modifing the killTimer() function AbstractJdbc2Statement.java:
> private synchronized void killTimer()
> {
> if ( cancelTimer != null )
> {
> cancelTimer.cancel();
> Driver.getCancelTimer().purge();
> cancelTimer = null;
> }
>
> }
> After modifing like above, i solved the problem.But i don't know
> if the solution is good.
> Thank you.
>
>