Why is this a problem? Are you seeing unacceptable slowness? It's fairly common for Java to frequently do GC, the problem happens when it uses stop-the-world GC. So unless you're seeing visibly slow performance I'd say ignore it.
Curiously, increasing the Java heap a little bit sometimes helps as I've seen situations where the GC recovers so little memory that another GC cycle immediately occurs. That said I don't see evidence of this in what you showed. GCViewer is a nifty tool for visualizing the GC activity BTW. Best, Erick On Mon, Feb 13, 2017 at 8:36 AM, Leon STRINGER <leon.strin...@ntlworld.com> wrote: > Hi, > > I get an issue where, when I'm deleting and adding Solr cores, it appears to > go > into a loop increasing CPU load and continually (every 2 seconds) logging to > the > garbage collection log. > > I had this problem with 6.1.0 so we've just upgraded to 6.4.1 and the issue > still occurs. The entries being logged every 2 seconds are below (hope it's > not > too verbose). Obviously this means the log gets big quickly. > > We can work around the issue by restarting Solr but presumably something has > gone wrong. Can anyone suggest if we're doing something incorrectly to cause > this, or if it's an issue we can troubleshoot. > > Any advice gratefully received. > > On CentOS 7 with OpenJDK 1.8.0_91-b14. > > solr_gc.log.0.current logs the following every 2 seconds: > > 2017-02-13T16:19:11.230+0000: 5092.640: [GC (CMS Initial Mark) [1 > CMS-initial-mark: 225270K(393216K)] 225280K(502464K), 0.0030517 secs] [Times: > user=0.01 sys=0.00, real=0.01 secs] > 2017-02-13T16:19:11.234+0000: 5092.643: Total time for which application > threads > were stopped: 0.0033800 seconds, Stopping threads took: 0.0000473 seconds > 2017-02-13T16:19:11.234+0000: 5092.643: [CMS-concurrent-mark-start] > 2017-02-13T16:19:11.359+0000: 5092.769: [CMS-concurrent-mark: 0.125/0.125 > secs] > [Times: user=0.50 sys=0.00, real=0.12 secs] > 2017-02-13T16:19:11.359+0000: 5092.769: [CMS-concurrent-preclean-start] > 2017-02-13T16:19:11.361+0000: 5092.771: [CMS-concurrent-preclean: 0.002/0.002 > secs] [Times: user=0.00 sys=0.00, real=0.00 secs] > 2017-02-13T16:19:11.362+0000: 5092.771: [GC (CMS Final Remark) [YG occupancy: > 10 > K (109248 K)]{Heap before GC invocations=3236 (full 1150): > par new generation total 109248K, used 10K [0x00000000e0000000, > 0x00000000e8000000, 0x00000000e8000000) > eden space 87424K, 0% used [0x00000000e0000000, 0x00000000e0001020, > 0x00000000e5560000) > from space 21824K, 0% used [0x00000000e6ab0000, 0x00000000e6ab1830, > 0x00000000e8000000) > to space 21824K, 0% used [0x00000000e5560000, 0x00000000e5560000, > 0x00000000e6ab0000) > concurrent mark-sweep generation total 393216K, used 225270K > [0x00000000e8000000, 0x0000000100000000, 0x0000000100000000) > Metaspace used 176850K, capacity 179580K, committed 181092K, reserved 1210368K > class space used 18794K, capacity 19506K, committed 19836K, reserved 1048576K > 2017-02-13T16:19:11.362+0000: 5092.771: [GC (CMS Final Remark) > 2017-02-13T16:19:11.362+0000: 5092.771: [ParNew > Desired survivor size 20112992 bytes, new threshold 8 (max 8) > - age 2: 160 bytes, 160 total > - age 4: 32 bytes, 192 total > : 10K->6K(109248K), 0.0041872 secs] 225280K->225276K(502464K), 0.0042455 secs] > [Times: user=0.01 sys=0.00, real=0.01 secs] > Heap after GC invocations=3237 (full 1150): > par new generation total 109248K, used 6K [0x00000000e0000000, > 0x00000000e8000000, 0x00000000e8000000) > eden space 87424K, 0% used [0x00000000e0000000, 0x00000000e0000000, > 0x00000000e5560000) > from space 21824K, 0% used [0x00000000e5560000, 0x00000000e5561830, > 0x00000000e6ab0000) > to space 21824K, 0% used [0x00000000e6ab0000, 0x00000000e6ab0000, > 0x00000000e8000000) > concurrent mark-sweep generation total 393216K, used 225270K > [0x00000000e8000000, 0x0000000100000000, 0x0000000100000000) > Metaspace used 176850K, capacity 179580K, committed 181092K, reserved 1210368K > class space used 18794K, capacity 19506K, committed 19836K, reserved 1048576K > } > 2017-02-13T16:19:11.366+0000: 5092.775: [Rescan (parallel) , 0.0018980 > secs]2017-02-13T16:19:11.368+0000: 5092.777: [weak refs processing, 0.0004940 > secs]2017-02-13T16:19:11.368+0000: 5092.778: [class unloading, 0.0580950 > secs]2017-02-13T16:19:11.426+0000: 5092.836: [scrub symbol table, 0.0110875 > secs]2017-02-13T16:19:11.438+0000: 5092.847: [scrub string table, 0.0019072 > secs][1 CMS-remark: 225270K(393216K)] 225276K(502464K), 0.0780250 secs] > [Times: > user=0.09 sys=0.00, real=0.08 secs] > 2017-02-13T16:19:11.440+0000: 5092.849: Total time for which application > threads > were stopped: 0.0782677 seconds, Stopping threads took: 0.0000411 seconds > 2017-02-13T16:19:11.440+0000: 5092.849: [CMS-concurrent-sweep-start] > 2017-02-13T16:19:11.546+0000: 5092.955: [CMS-concurrent-sweep: 0.106/0.106 > secs] > [Times: user=0.11 sys=0.00, real=0.11 secs] > 2017-02-13T16:19:11.546+0000: 5092.955: [CMS-concurrent-reset-start] > 2017-02-13T16:19:11.546+0000: 5092.956: [CMS-concurrent-reset: 0.001/0.001 > secs] > [Times: user=0.00 sys=0.00, real=0.00 secs] > > Regards, > > Leon Stringer