tomcat-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Pid <...@pidster.com>
Subject Re: Bug in Tomcat AJP Connector?
Date Thu, 05 Apr 2012 23:45:13 GMT
On 05/04/2012 22:17, Ofer Israeli wrote:
> Y
> 
> On 5 באפר 2012, at 18:58, "Konstantin Kolinko" <knst.kolinko@gmail.com> wrote:
> 
>> 2012/4/5 Ofer Israeli <oferi@checkpoint.com>:
>>> Mark Thomas wrote:
>>>> On 04/04/2012 17:02, Ofer Israeli wrote:
>>>>
>>>> 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.
>>>>
>>>> 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 precautious 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 garbage around after the thread's death.
>>> Do you see any reason as not to close the listening socket?
>>>
>>
>> 1. Tomcat does not start JVM  thus it cannot restart it.
>>
>> You need some external tool or script or admin to perform monitoring
>> and (re)starts.
>>
>> 2. OOM can happen at a random place. Once it happens, it is likely
>> that other places will also start to fail randomly. It is also likely
>> that your attempts to recover will fail as well.
>>
>> Mark already mentioned it: "all bets are off".
>>
>> Best regards,
>> Konstantin Kolinko
>>
> Hi Konstantin,
> 
> I agree regarding the OOM bringing TC to a state where it must be restored, but my point
remains: if there is code that handles catching this exception and terminating the thread,
why not terminate gracefully by closing the listening socket before killing the thread?

And your point has been answered.  After an OOM the JVM is in an
unknown, unsafe state so a restart MUST occur to restore service.

Closing a socket gracefully after an OOM is a bit like trying to shut
one of the portholes on the Titanic, shortly after hearing a large
crashing sound.


There's only one place I know of where Tomcat attempts to interact with
OOM conditions and this is not one of them, so I don't believe it's safe
to say that Tomcat is deliberately handling this exception.

NB an OOM is an Error, not an Exception - it is a subclass of
VirtualMachineError, which is thrown to indicate that the Java Virtual
Machine is broken or has run out of resources necessary for it to
continue operating.

An Error is a subclass of Throwable that indicates serious problems that
a reasonable application should not try to catch.
</end-quote>

If anything, the locations where Tomcat catches a Throwable should be
modified so it does *not* catch Errors, rather than continuing to do so
and then attempting a trivial tidy-up.


p


-- 

[key:62590808]


Mime
View raw message