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From André Warnier>
Subject Re: a problem: tomcat exits unexpectedly
Date Mon, 06 Oct 2014 07:20:44 GMT
bo zhao wrote:
> Warnier,
>     Thank you for your reply.
>     AbstractScheduleTaskProcess class use the ExecutorService to create
> thread and runs some custom tasks. These tasks will be done in a few
> seconds. Sample code is following:
>    for (final List<T> list : lists) {
>             executor.submit(new Callable<Object>() {
>                 @Override
>                 public Object call() throws Exception {
>                     try {
>                         executeTasks(list);
>                          ......
>     But I don't think that this class causes the serious prolbem. the max
> size of "lists" is 4 -- that is a parameter of application.
>     In our server, we have 12 tomcat instances that run the different
> application, but the default value of os parameter(open files and max
> processes) is 1024, at first, I modified these value to 65535. but some of
> these instance had still exited unexpectedly, I has found the same things
> in these log:  pause, reinit, stop. So I think that the os resource limit
> maybe cause all of these, especially the parameter of the "open files".
>     I don't know well the tomcat, so I maybe has not found the key cause
> and I expect your reply.

In such circumstances, you can (probably) consider Tomcat as "just a process" like any 
other.  It looks like something in that process is holding on to a lot of open files/sockets.
The Linux utility "lsof" provides (among a zillion other things) a good way to list all 
the files/sockets linked to one process.
Try it for one of your Tomcat instances, and probably the names of these files/sockets 
will give you a hint.

>     Thank you very much.
> On Sun, Sep 28, 2014 at 6:37 PM, André Warnier <> wrote:
>> bo zhao wrote:
>>> I had modified the os ulimit parameter: open files and max processes,
>>> after
>>> that, Tomcat does't exit unexpectedly, and the log of Tomcat have not the
>>> "... pause, ... init". It seems work normally.
>>> But I still don't know the reason. I want to know if the two parameter is
>>> the key to solve probelm and how the two parameter of os limit cause the
>>> exit of tomcat?
>> I believe that you are understanding this wrongly.  These paraneters are
>> not the /cause/ of the problem, they are a /symptom/.  The default value fo
>> these parameters is set so that they are ok for any normal process/system,
>> and rarely need to be adjusted.
>> By increasing their value, you are moving the problem further down the
>> line, but are not solving the real (possible) problem.
>> Ognjen is asking a question below. Why do you not start by answering it ?
>>> On Fri, Sep 19, 2014 at 5:17 PM, Ognjen Blagojevic <
>>>> wrote:
>>>  Zhao,
>>>> On 19.9.2014 3:42, bo zhao wrote:
>>>>  but I can't find any error message in the log? what causes the tomcat to
>>>>> pause and stop?
>>>>>  One of the suspects for restarts and shutdown seems to be the class
>>>>, as there is a
>>>> log message regarding it, at the first line of each log excerpt you sent.
>>>> What is AbstractScheduleTaskProcess class for?
>>>> -Ognjen
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