Servlet throughput slows to a crawl
06/20/12 9:11 PM
Under some load test circumstances, we're seeing the following set of symptoms; we also believe was have seen this in production, although our instrumentation at the time wasn't as complete as in our load test environment.
* Throughput drops to a crawl, from a healthy rate of 50 - 200 receipts per minute per servlet, to 1-2 per minute. * CPU drops to essentially zero. * Examination with Yourkit shows no thread blocking which could explain slow throughput. * The database shows no blocking which could explain the low throughput. * Examination with Yourkit shows almost no request threads; at most time points there are none, confirming that there aren't blocked or long-lived threads. * The load tester still reports very good page times on the small number of requests which are being processed.
It appears that requests are not getting to ServletExec, but in such a way that the load tester is not seeing a significant response delay. We're unsure how to trouble-shoot this problem.
Environment is ServletExec 6.0 AS under Windows 2003 server / IIS 6 (64bit) , with JDK 1.6.21 (32 bit).