I've searched for this about one week, and still no answer. I'm not sure what this problem is about

I 've been using MySql 4.1, Tomcat 5, hibernate2, Spring 1.1.5 together without problem.

Until i changed the DriverManagerDataSource of Spring into a connection pooling source; C3P0 0.9.0 pre6 (or DBCP)

Now, after some time like 5-10 mins (i guess time decreases with concurrent user count), tomcat gives an error :

org.apache.tomcat.util.threads.ThreadPool logFull
SEVERE : All threads(150) are currently busy, waiting. Increase maxThreads or check servlet status


After this error, tomcat doesnt let any other connection.

Ofcourse, i tried to increase max thread, just delayed the error.

I dont think this is something about MySql, because same error with different consequences happens with Oracle too.

I dont know what to do. Somehow, somewhere threads are not being released

Any guidance would be appreciated.

the requests aren't finished. this can be a bug somwhere in your app. on linux you can use kill to get stacktraces of all the threads and find out where they hang.

close session, it will return connection to pool.

thx for reply chrigi

it works without connection pooling, which made me think i'm doing something wrong about one of the frameworks, most probably hibernate or pool library.

anyway, do you know, in windows how can i find where threads are stuck?

Place these lines between <resource> </resource> of the


in the (assuming tomcat 5.0) ../conf/Catalina/localhost/(your_application).xml

<parameter>
<name>removeAbandonedTimeout</name>
<value>60</value>
</parameter>
<parameter>
<name>logAbandoned</name>
<value>true</value>
</parameter>
</ResourceParams>

Place these lines in your application's config file where you configure the connection pool. I am assuming DBCP.

(assuming tomcat 5.0)your application's config file will be ../conf/Catalina/localhost/(your_application).xml

<parameter>
<name>removeAbandonedTimeout</name>
<value>60</value>
</parameter>
<parameter>
<name>logAbandoned</name>
<value>true</value>
</parameter>
.
.
.
</ResourceParams>

This gives lots of logs which may help you pin point the location of the problem.

Cheers - I think, therefore I survive.
J2EE_pro

Just find Filter implementation for spring to close connections (see some spring example and paste filter configuration to web.xml)

baliukas, do you mean OpenSessionInViewFilter? I'm using OpenSessionInViewInterceptor, and what i see from its log outputs, it seems to be flushing and closing session

anyway, if it wouldnt close session, the code without connection pooling would run out of resources soon too, am i wrong?


(J2EE_pro : thx, but i couldnt make it work, no more logs...)

Try "kill -3" or "Ctrl + Pause" on windows, you will see stack trace for all threads, but it looks like connection is not returned to pool and threads block in "getConnection()" ( or plian connection startup is faster than pool).