I monitored it using Yourkit profiler and I didn't see any extreme GC. I noticed anotehr thing : looking for 4 users which had the problem they seems to have the problem "in sequence".
The first user "stops" for 4 seconds then another one "stops" and so on : they don't seem to stop at the sam time (as it would be expected in case of GC) but in sequence. Tks ________________________________ Da: André Warnier (tomcat) <a...@ice-sa.com> Inviato: lunedì 17 ottobre 2016 18.01 A: users@tomcat.apache.org Oggetto: Re: Strange wait time in my application - Tomcat 7.0.67 On 17.10.2016 17:52, Tullio Bettinazzi wrote: > I didn't find any solution to my problem. > > Could someone provide suggestions or a strategy to find the solution ? > "I don't see relevant garbage collection : heap size and permgen have correct dimentions." Define "correct". Are you really *logging* the JVM Garbage Collection, and do you *know* that this is not the issue ? (Note that 4 seconds seems an awfully long time for a GC; but one would want to eliminate this with certainty, before looking any further). > > > ________________________________ > Da: Martijn Bos <mart...@maboc.nl> > Inviato: lunedì 3 ottobre 2016 21.05 > A: Tomcat Users List > Oggetto: Re: Strange wait time in my application - Tomcat 7.0.67 > > On 2016-10-03 07:56:34, Tullio Bettinazzi wrote: >> I've an application under tomcat. >> When only a one or two users works on it everithing is ok. >> When the number of users grows the application slows down. >> Is not a memory nor a cpu problem : using top I see the system resources >> quite free. >> I don't see relevant garbage collection : heap size and permgen have correct >> dimentions. >> No other applications are running on the system. >> I log more or less every relevant operation in my system (db query and so >> on) and I see that every slowdown is concentered in a single operation. >> I mean all operations take "normal" time but one or two of them take 4 >> seconds more. >> The "slowing" operations are not the same in different executions, and >> theydo not have a specific type (not only DB query, not only DB stored >> procedures, not only.....). >> It seems like if the thread is frozen for a fixed amount fo time (4 seconds >> more or less) and then it restarts. >> I don't think it's a "queue" problem because otherwise the wait time would >> be unperdictable and not a "fixed" 4 seconds time. >> I don't know any parameter impacting on that behaviour. >> I use Tomcat 7.0.32 with JVM 1.7.0.67 on a Linux server. >> Could someone suggest a solution for my problem or, at least, an >> investigation strategy. >> Tks >> >> Tullio >> > > > The few examples that you mention are all database related (query/stored > procedure). > Can it be that your connection pool (if used) combined with not closing > connections is part of the problem. > > I can imagine : > 1) > Maybe you run out of conenctions, because connections are not properly closed. > And also the connection pool teminates connections when they are not used for > 4 seconds. > After 4 seconds the pool can recreate connections again. > > or 2) > Maybe your connection pool has very limited connections. > With one or two users this limited number of connections in the pool will > suffice. > If there are more users, the max. number of connections isn't enough. > The pool then has to wait for connections to become fee again. > > > (uhh....I'm not an expert at all, but the above came immediately to my mind) > > -- > Met vriendelijke groet, > > Martijn Bos > +31 6 39477001 > > (Public pgp-key : http://maboc.nl/pubkey.maboc.asc) maboc.nl<http://maboc.nl/pubkey.maboc.asc> maboc.nl -----BEGIN PGP PUBLIC KEY BLOCK----- Version: GnuPG v1 mQENBFJ6LpgBCADL9w2eicatZKiw4xijCVC8WZpcPOr2So6jFfQ6nWk3bTXoVsHk sYgdLIFeCn9Wn+EeC+CSoosyMcUeijKH5yVqc/mcg0 ... > maboc.nl<http://maboc.nl/pubkey.maboc.asc> maboc.nl<http://maboc.nl/pubkey.maboc.asc> maboc.nl -----BEGIN PGP PUBLIC KEY BLOCK----- Version: GnuPG v1 mQENBFJ6LpgBCADL9w2eicatZKiw4xijCVC8WZpcPOr2So6jFfQ6nWk3bTXoVsHk sYgdLIFeCn9Wn+EeC+CSoosyMcUeijKH5yVqc/mcg0 ... > maboc.nl > -----BEGIN PGP PUBLIC KEY BLOCK----- Version: GnuPG v1 > mQENBFJ6LpgBCADL9w2eicatZKiw4xijCVC8WZpcPOr2So6jFfQ6nWk3bTXoVsHk > sYgdLIFeCn9Wn+EeC+CSoosyMcUeijKH5yVqc/mcg0 ... > > > > --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
