XWiki and Tomcat crashes

Hi everybody!

we experience a strange behaviour with our XWiki 10.1+1 installation on Ubuntu 16.04 with Tomcat 8.0.32-1ubuntu1.5, Mysql 5.7.21 and Java 1.8.0_161. After ~1 minute permanent use, XWiki gets more and more slowly until the whole Tomcat freezes and we need to restart the Tomcat service. When nobody used XWiki for a day, Tomcat and XWiki still running the next morning. In the logs of Tomcat and Mysql we didn´t find any relatet infos, even when we set a higher information level in the XWiki administration page. Tomcat, the Ubuntu system and the java environement have enough memory space left and the processor isn´t fully occupied.

Maybe someone has an idea how to investigate our problem.

Thanks in advance

You should take a Java thread dump. It will allow you to see what’s running exactly (and block everything). Maybe take several (with a few minutes between each of them) so that you can see what exactly keep running in all the reports.


Thanks for the input.
We located in the Java thread dump a blocking function. It seems, that the notification plugin of XWiki keeps blocking the jvm and after deactivating the notifications in XWiki we have a smooth running system for the last days. Are there any similar problems regarding the notification function in the current xWiki release and we maybe need to wait for an update or are there any other options to get the functionality of the notifications back?

We did noticed performances issue (but not as bad as the one you have) recently but it’s true that the timing is consistent with new notifications module introduction. We did not analyzed it much yet.

If there is nothing in them preventing you to share the thread dump you took it would be very interesting to see them.

Could you please explain which notification feature you disabled? Did you use notifications.enabled = false?

Do you have the same problem if you only disable notifications.emails.enabled?

Thanks for your help,