-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 André,
On 11/24/13, 7:29 AM, André Warnier wrote: > Hi. This is not a pure Tomcat question, just related. I hope that > the Java expertise present on this list might allow a quick rough > answer. > > OS : Debian 3.2.46-1~bpo60+1 i686 GNU/Linux > > Java info : # java -server -version java version "1.6.0_26" > Java(TM) SE Runtime Environment (build 1.6.0_26-b03) Java > HotSpot(TM) Server VM (build 20.1-b02, mixed mode) > > System memory usage info: # free total used free > shared buffers cached Mem: 3114844 2947360 > 167484 0 17768 2372508 -/+ buffers/cache: > 557084 2557760 Swap: 5859324 39360 5819964 > > Question: > > One of our Linux systems is running a background permanent Java > process, started with the following command-line options : > > ./java -server -Xms128M -Xmx128M -Xloggc:/home/xxx/xxx_gc.log > -XX:+PrintGC -XX:+PrintGCTimeStamps ... -jar jar-file.jar > > My question is just : to a Java expert eye, does the following GC > trace look "normal" , or "pathological", or in-between ? (and > accessorily, how does one interpret the leading timestamp ? > seconds.milliseconds since JVM start ?) > > > Sample contents of the GC logfile : > > ... 3484797.072: [Full GC 1607K->753K(126720K), 0.0415410 secs] > 3507300.493: [Full GC 6651K->799K(126720K), 0.0239830 secs] > 3508197.401: [Full GC 1507K->839K(126720K), 0.0247090 secs] > 3508703.684: [GC 35782K->1485K(126720K), 0.0014440 secs] > 3509098.112: [Full GC 9245K->888K(126720K), 0.0603780 secs] > 3509997.732: [Full GC 1596K->753K(126720K), 0.0231020 secs] > 3510897.991: [Full GC 1461K->794K(126720K), 0.0389760 secs] > 3511797.605: [Full GC 1501K->834K(126720K), 0.0230580 secs] > 3512697.608: [Full GC 18190K->890K(126720K), 0.0263780 secs] > 3513597.620: [Full GC 1598K->753K(126720K), 0.0469200 secs] > 3514497.557: [Full GC 1460K->793K(126720K), 0.0382910 secs] > 3515397.128: [Full GC 1501K->834K(126720K), 0.0232420 secs] > 3516298.110: [Full GC 33765K->906K(126720K), 0.0270450 secs] > 3517197.288: [Full GC 1468K->753K(126720K), 0.0451560 secs] > 3518098.189: [Full GC 34605K->826K(126720K), 0.0526920 secs] > 3518997.666: [Full GC 1338K->866K(126720K), 0.0232330 secs] > 3519897.722: [Full GC 2859K->908K(126720K), 0.0237370 secs] > 3520617.399: [GC 35852K->2220K(126720K), 0.0029720 secs] > 3520797.213: [Full GC 7599K->760K(126720K), 0.0496770 secs] > 3521698.220: [Full GC 1431K->801K(126720K), 0.0260610 secs] > 3522597.525: [Full GC 1508K->841K(126720K), 0.0230380 secs] > 3523497.230: [Full GC 1549K->881K(126720K), 0.0351840 secs] > 3524397.728: [Full GC 1590K->753K(126720K), 0.0439350 secs] > 3525297.762: [Full GC 1461K->794K(126720K), 0.0357500 secs] > 3526197.104: [Full GC 1501K->834K(126720K), 0.0231210 secs] > 3527098.242: [Full GC 1542K->874K(126720K), 0.0277570 secs] > 3527997.312: [Full GC 1582K->754K(126720K), 0.0455090 secs] > 3528898.282: [Full GC 26344K->818K(126720K), 0.0307250 secs] > 3529797.050: [Full GC 1381K->858K(126720K), 0.0261330 secs] > 3530698.086: [Full GC 1567K->899K(126720K), 0.0243030 secs] > 3531597.998: [Full GC 1606K->754K(126720K), 0.0250980 secs] > 3532498.797: [Full GC 1462K->794K(126720K), 0.0335000 secs] > 3533398.598: [Full GC 1502K->834K(126720K), 0.0229160 secs] ... My advice is to graph the data. If you get a sawtooth pattern, that's good. If the troughs of the saw-tooth pattern are fairly consistent, then you have a memory-stable web application. Load testing + graphing GC activity is a great exercise. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJSk6MUAAoJEBzwKT+lPKRYzhIQAMTwZ69lYqjgfv88jWdMwgd+ rUJ7F7N9wbA4IFtu6fV1nRk7PYmok3C/iyAvHunHTSB6YgZP1EB0lVdRk2bSeKOw qDgDEJj3Mr+IjkfDoxQX0PoGgzLAD5245ze/2l+jJSx1VQIyyLXl0kQ++jSopteS XZ4U06XqT8UlQi1WMgrcQNDjCTKF2oWaQhyZRRJgbvA3tofoZWohxBxN59Gx+WAt SsNdLr3acTCmpnMJd8bk2faKPNZlOgrR6ajggRQ5+IS1pTjDg8KvzfDmKPu3kRQy JHvxCkoObz9kfEIOyWo392uWdTJxZhagnn4K/GxP7S/pU9Ibhg9TuemXDiwf2A18 v6eWfxzi0u+DurYBKKoLmdW3sUZpAhGORlWm5BJ/2iYf+Qbem0RpB3H9KBbQgDXw WAHmBjxdwYcrkKETKf4az7QCvN9eQbPIaRljtkbGZXO521W7HME04iJ5ZEH+9w7z W1jyjBdHUL7D9uR0ZKrYeaGzThVwXFQJEjCJjpiG1Us/xP9ws1h+RuTbGEF1onBu B3w8mBNoGE1+/IFbuoCclOwEM/iHmZWnSywu5+gwPjUlzOTmpoJ+SC4gwXaQ8ciQ ZtmBGySdK3Ugn6lU+L+nzoQYiuq8kyphLwEVIZVx5kEq4Z1EgWh2H0Wlaet0cr3o JAuX+kfIwupqTYALaZ+7 =mdu0 -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
