William, Have you tried running with a lower number (than the current 18) of parallel workers?
On Tuesday, August 30, 2016, William Good <bkg...@gmail.com> wrote: > I've been experiencing an issue in a production application using G1 > for quite some time over a handful of 1.8.0 builds. The application is > relatively simple: it spends about 60s reading some parameters from > files on disk, and then starts serving web requests which merge some > input with those parameters, performs some computation and returns a > result. We're aiming to keep max total request time (as seen by remote > hosts) below 100 ms but from previous experience with parnew and cms > (and g1 on previous projects, for that matter), I didn't anticipate > this being a problem. > > The symptoms are an ever-increasing time spent in evacuation pauses, > and high parallel worker termination times stick out. With the > recommended set of G1 settings (max heap size and pause time target), > they increase sharply until I start seeing 500ms+ pause times and have > to kill the JVM. > > I found some time ago that first forcing a bunch of full GCs with > System.gc() at the phase (load -> serve) change and then forcing > frequent concurrent cycles with -XX:InitiatingHeapOccupancyPercent=1 > seems to mitigate the problem. I'd prefer to have to do neither, as > the former makes redeployments very slow and the latter adds a couple > of neighboring 40ms pauses for remark and cleanup pauses that aren't > good for request time targets. > > I'm attaching a log file that details a short run, with the phase > change at about 60s from start. After a few evacuation pauses, one > lasts 160ms with nearly 100-120ms spent in parallel workers' > 'termination'. After this, a concurrent cycle runs and everything goes > back to normal. java params are at the top of the file. > > Generally this happens over a much longer period of time (and > especially if I haven't given the low > -XX:InitiatingHeapOccupancyPercent value) and over many different > builds of 1.8.0. This was b101. It's running alone on a fairly hefty > dual-socket Xeon box with 128GB of RAM on CentOS 7. > > I'd be more than happy to hear any ideas on what's going on here and > how it could be fixed. > > Best, > William > -- Sent from my phone
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