We are running apache and tomcat on the same machine (using the http connector) and logging requests in both. Occasionally (maybe 1% of requests) we see 502 response in the apache log spread fairly evenly throughout the day. these requests don't appear in the tomcat log produced by the access valve. in the apache error log I see:
proxy: error reading status line from remote server 127.0.0.1 proxy: Error reading from remote server returned by [url] The requests are a mix of methods (GET/POST/PUT) of pretty small bodies and responses, generally under 1k. We added request time (%T) in the apache logs and many of the requests have 0 response time so I don't think it's a timeout issue. Reading the tomcat connector documentation, I tried increasing the maxThreads to 100 and backlog to 1000 in the http connector since it seemed like with the default settings a burst of traffic may cause this issue. This didn't solve the problem. I have done periodic thread dumps and it looks like the number of http threads doesn't get past 80. concerning machine resources, cpu is not loaded at all (~10% utilization). i checked file descriptor usage, it's about 400 and there is a per process limit of 1024. I am not sure if this should be posted to the apache list or tomcat list, but thought i would start here since to me it seems more likely that I am not configuring tomcat correctly as opposed to some problem in apache. I have searched the web quite a bit, but nothing seems to fit. The next thing I will try is to use the AJP connector. But even if it gets rid of the problem, I am worried it may reappear once traffic increases. Has anyone experienced a similar problem? other stuff: OS: CentOS apache: 2.2.3, using mod_proxy tomcat: 6.0.16 using netstat, i see a moderate number (~80) of tomcat's sockets in the CLOSE_WAIT state, not sure if this is relevant. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
