Deadlock in mongodb java driver

Question

I have multithreaded java application with my ~5 threads (and also many threads from jetty web server), some of them are reading/writing mongodb from time to time. Some of writes are intensive, where I read 200K mongodb objects, but they don't happen continiously, they happen once in few minutes. For few hours application works perfectly, but later I see this situation:

Mongo is not doing any work, as far I understand it:

Here is my jstack output:

https://gist.github.com/stiv-yakovenko/06b0d235fd2c32d839788edf56aaa6cd

You can see that all threads are waiting for one thread, which, in turn is waiting for mongo, while mongo is doing nothing . Before problem begings, healthy situation is that no threads are waiting for anyone else, because load is not that high to block everything. Before mongo I was using mapdb to store same data and I never had issues like that.

I've seen same situation with multiple threads waiting for mongo, so I decided to put all mongodb invocations under the same ReentrantLock(true). I hoped that rootcause was too many threads wanted to access mongo, but it doesn't help. I don't know what to do, tried to reproduce the problem with simple code, but I can't. Any ideas?

UPD: here is jstat output as one of commenters requested:

Answer 1

Well, finally it turned out that it was a garbage collection. I've ended up using G1 garbage collector. But it was not enough, because it couldn't deliver required latency (though it was close to it). I had to split application into two parts, one for doing intensive garbage-producing calculations, another for low-latency web responses.