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From <msl...@email.cz>
Subject Re: Re: JVM hangs during startup (indexing) (2)
Date Fri, 08 Mar 2013 09:16:02 GMT
I checked 2 thread dumps you provided so I can only comment what I saw 
there. I did not see any deadlock. Only
problem I saw was in main thread where it was waiting for connection.

   "main" prio=10 tid=0x0000000040feb000 nid=0x4fb0 in Object.wait() [0x
      java.lang.Thread.State: WAITING (on object monitor)
           at java.lang.Object.$$YJP$$wait(Native Method)
           at java.lang.Object.wait(Object.java)
           at java.lang.Object.wait(Object.java:485)
           at org.apache.commons.pool.impl.GenericObjectPool.borrowObject
           - locked <0x00000000d9b90c40> (a org.apache.commons.pool.impl.
           at org.apache.commons.dbcp.PoolingDataSource.getConnection
           at org.apache.commons.dbcp.BasicDataSource.getConnection
           at org.apache.jackrabbit.core.util.db.ConnectionHelper.

You should be able to get thread dump any time unless JVM process is 
completely frozen IMO. Do you use jstack to get thread dump?


---------- Původní zpráva ----------
Od: Daniel Hobi <d.hobi@gmx.ch>
Datum: 8. 3. 2013
Předmět: Re: JVM hangs during startup (indexing) (2)

"Hi Marek

Thanks for your suggestions!

Unfortunately, changing the JVM gc options so that the JVM will no longer 
hang just worked ONCE.
Therefore I was not able to get a "nice" stack trace anymore :-(

Connection Pool:
We had set the max connection pool size to 5. As you suggested I set it to 
15. Same effect. Even 50 or 100 did not help.
Interestingly, postgres shows just 3 open connection for jackrabbit. Is this
a suspicious behavior or does it simply not need more connections and is 
therefore not spawning new connections?

Enabling debug, setting login and socket timeout on the postgres-jdbc-driver
did not help either.
I even changed the pool implementation from dbcp to c3p0 in jackrabbit-core-
2.6.0 to be "sure" it is not a pool bug.
Further we are not able to reproduce the hang with:
- Slower machine, postgres 8.3
- Very fast machine, postgres 8.4 (only hanged 1 of 5 times so far)
- Faster machine, mysql

This issue is slowly driving me nuts ;-)


Am 07.03.2013 um 16:24 schrieb mslama@email.cz:

> Also randomly we had problem with not released connections in JBoss 
> connection pool and Postgres. Now long time no occurrence.
> In any case you can check number/list of open connections in psql . In our

> case it was
> 97 open connection (by default 100 open connections in postgres and 3 are 
> reserved for admin). It happenned even if we had much smaller
> max connection pool size. As it happened randomly we did not find any 
> solution. We tried to change connection pool size and it does not
> happen any more. Still no idea what was cause of this. In any case using 
> psql you can find out easily if it is also your problem.
> Query is for 9.x: SELECT * FROM pg_stat_activity;
> Marek
> -- 
> Marek Slama
> mslama@email.cz
> ---------- Původní zpráva ----------
> Od: mslama@email.cz
> Datum: 7. 3. 2013
> Předmět: Re: JVM hangs during startup (indexing) (2)
> "Quick look: It hangs in connection pool - connection pool if it cannot 
> return free connection to caller it waits forever by default.
> How big is your connection pool? (Maximum size? It would be good to patch 
> connection pool to see who/how many connections is
> used and why connections are used not release. In our config we use 
> connection max pool size 15 and it is enough.) So first
> fast fix would be to increase max connection pool size but if there is 
> problem with not released connection it will not help for long.
> Good news is it is not problem with memory or gc (at least IMO).
> Marek
> -- 
> Marek Slama
> mslama@email.cz
> ---------- Původní zpráva ----------
> Od: Daniel Hobi <d.hobi@gmx.ch>
> Datum: 7. 3. 2013
> Předmět: JVM hangs during startup (indexing) (2)
> "Hi there
> Some updates on our issue started here:
> http://mail-archives.apache.org/mod_mbox/jackrabbit-users/201301.mbox/%3C
> 30115135117.186960%40gmx.net%3E
> We're still facing the JVM freeze (possibly during minor gcs) even if...
> ...we updated Jackrabbit from 2.2.13 to 2.6.0.
> ...we updated the Sun JVM to the latest version (1.6.39) and even tried
> OpenJDK.
> ...we increased the JVM heap size (up to 1.5gb).
> ...we upgraded PostgreSQL to the latest version (8.4.x / 9.2.x) available.
> But there is good news too:
> - I've just played around with the JVM's garbage collection
> options. Even if the index process still hangs the JVM will no longer 
> I was able to get an interesting thread dump:
> <http://pastebin.com/uSrXpej8> http://pastebin.com/uSrXpej8
> - With the addition JVM Param -XX:MaxNewSize=10m we can make the
> hang occur faster (less than 100 minor gcs)
> I would be very grateful if someone could have a look at this. We're 
> (slowly but surely) out of ideas :-(
> Thanks!
> Daniel"""
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