On 05/09/2010 03:19, Kevin wrote: > Hi, I'm using Apache Bench (ab) to send 1,000 requests with a > concurrency of 500 to a simple servlet on Tomcat trunk (revision 992708, > 2010-09-03) which uses request.startAsync() and > Executors.newFixedThreadPool(10) to do the work and return a few bytes > of response and asyncContext.complete(). > > What I'm noticing is that every once in a while there is an errant > request that takes up to 10 seconds, while the average is around half a > second. I've reproduced this on both Oracle and IBM JVMs. I've looked at > verbosegc and see no anomalies in pause times or heap usage. I've taken > javadumps and I don't see any thread that is obviously "stuck" anywhere. > Most importantly, if I compare this to a servlet that writes the same > bytes but synchronously (i.e. a "classic" servlet service() method), > then I don't see this aberration. > > I can see these long requests in my access log by changing > org.apache.catalina.valves.AccessLogValve to "%h %l %u %t "%r" > %s %b %D", e.g.: > > 127.0.0.1 - - [04/Sep/2010:18:46:20 -0700] "GET /myapp/ HTTP/1.0" 500 > 207 10986 > 127.0.0.1 - - [04/Sep/2010:18:46:22 -0700] "GET /myapp/ HTTP/1.0" 500 > 207 10428 > 127.0.0.1 - - [04/Sep/2010:18:46:22 -0700] "GET /myapp/ HTTP/1.0" 500 > 207 10347 > > My question is: how do I debug these 500 errors?
Which OS are you using? One of the (non-access) log files in tomcat/logs might have a stacktrace in it. If not, then you might need to configure an UncaughtExceptionHandler, set on a thread when it's created in a ThreadFactory - which you can supply as a parameter to most Executors.newXXXXXThreadPool methods. p > Thanks. > > --------------------------------------------------------------------- > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org >
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