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From: Ofer Israeli <oferi@checkpoint.com>
To: Tomcat Users List <users@tomcat.apache.org>
Date: Thu, 5 Apr 2012 10:31:31 +0300
Subject: RE: Bug in Tomcat AJP Connector?
Thread-Topic: Bug in Tomcat AJP Connector?
Thread-Index: Ac0ShpqUxaPBmRK+TNGu5OyPC+ytdgAdyjUg
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Mark Thomas wrote:
> On 04/04/2012 17:02, Ofer Israeli wrote:
>> Hi all,
>>=20
>> We have recently witnessed a strange situation.  Our Tomcat (6.0.35)
>> listens on 2 ports: 8080 and 8009, handling HTTP and AJP
>> respectively. At some point in time we found that Apache is replying
>> HTTP 503s to all clients and a look at netstat showed that indeed
>> Apache could not communicate with Tomcat - there were many
>> connections in state SYN_SENT, that were never replied.  A test of
>> attempting to connect to Tomcat's 8009 port turned out to give the
>> same result, so the issue was obviously in Tomcat and not Apache.
>> But netstat also showed that Tomcat was listening on port 8009.
>> After digging into the logs, we found that there was an Out of Memory
>> exception in the JK's accept() sequence and once this exception was
>> caught there was a message of "terminating thread".
>>=20
>> So although the exception is caught and handled by killing the thread
>> (isn't that a little drastic?), the socket isn't closed beforehand
>> and thus the OS thinks that the port is still fine (in LISTENING
>> state), as although the thread is dead, the process is alive.  Has
>> anyone encountered this or knows if this bug is known?
>=20
> Once you have an OOME all bets are off. The JVM needs to be restarted.
> There is no guarantee of reliable operation after an OOME.
>=20
> Mark

Hi Mark,
I agree that there in such a situation the JVM should be restarted, but it =
isn't restarted by Tomcat.  On the other hand, Tomcat does take some precau=
tious actions and kills the accepting thread, but in such a case it should =
also close the socket that thread is listening on otherwise it is leaving g=
arbage around after the thread's death.
Do you see any reason as not to close the listening socket?

Ofer=

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