-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Rainer,
On 3/25/15 6:18 AM, Rainer Jung wrote: > Am 24.03.2015 um 23:40 schrieb André Warnier: >> Rainer Jung wrote: >>> Some numbers from a test here on RHEL 6, using Java 1.7.0_76 >>> and TC 6.0.43, 7.0.59 and 8.0.20. >>> >>> Measurement is taken directly after start (a) plus once after >>> one request to a non-existing page and two full GCs (b). Only >>> manager was deployed, not example webapps or docs. GC was run >>> using "jcmd PID GC.run" >>> >>> Numbers from "ps" >>> >>> RSSa RSSb SZa SZb VSZa VSZb tc6 62372 68336 272952 >>> 273532 1091808 1094128 tc7 63608 70456 271710 271978 1086840 >>> 1087912 tc8 72576 79140 272257 272525 1089028 1090100 >>> >>> Differences between TC6 and 7 marginal, differences between tc7 >>> and 8 only noticable in RSS, around 9MB. >>> >>> Numbers from jstat -gc. First "Capacity": >>> >>> Semi Spaces start with 512KB and grow to 768.0KB (TC6), 896.0KB >>> (tc7) and 1024.0 (tc8). Those indicate increasing allocations, >>> but are not relevant for total memory use. >>> >>> Edena Edenb Olda Oldb Perma Permb tc6 4288.0 6656.0 >>> 10688.0 16320.0 21248.0 21248.0 tc7 4288.0 7168.0 10688.0 >>> 17904.0 21248.0 21248.0 tc8 6144.0 8640.0 15316.0 21316.0 >>> 21248.0 21248.0 >>> >>> Again this is capacity so including garbage and unused. We see >>> that Perm is unchanged. For all versions Eden grows by 2.4-2.9 >>> MB due to allocation activity. Numbers for tc6 and 7 are again >>> very similar, tc8 numbers are slightly higher already after >>> startup. Old (Tenured) grows by about 6-7MB, again very similar >>> for tc 6 and tc 7 and slightly higher for TC 8. >>> >>> Now for the used numbers after GC, which are more relevant >>> (allocation rates are another topic): >>> >>> Edena Edenb Olda Oldb Perma Permb tc6 2910.8 69.3 >>> 7231.7 7984.1 13923.0 14429.1 tc7 2326.1 73.8 8504.4 >>> 9661.2 13910.1 15340.1 tc8 203.7 60.9 10577.6 12599.7 >>> 16183.3 17653.8 >>> >>> So the live objects are Edenb+Oldb: >>> >>> Edenb+Oldb tc6 8053.4 tc7 9735.0 tc8 12660.6 >>> >>> And here we see some increase but the total amount of about >>> 2MB between tc 6 and 7 and about another 3 MB between 7 and 8 >>> seems to be not really problematic. The same holds true for >>> perm, there's an increase of about 1MB between 6 and 7 and 2 MB >>> between 7 and 8. >>> >>> Finally: where does the difference between RSS, Sz and the sum >>> of heap and eden come from? >>> >>> Example for TC 8 case b: >>> >>> RSS: 79140 SZ: 272525 >>> >>> Sum of RSS due to "smaps": 79088 so roughly consistent. >>> >>> S0+S1+E+O+P capacity: 53252, but Rss 40872, so a delta of 38MB >>> to RSS. >>> >>> smaps entries that can be identified: >>> >>> Type Size Rss Perm 21248 17656 Old 21316 >>> 15040 Eden+S0+S1 10688 8176 libjvm.so 11732 7712 >>> (read-only) >>> >>> Then about 21 thread stack reservations, total Size 21676, >>> total Rss 2804. >>> >>> So the delta goes down to 38 - 7.7 - 2.8 = 28MB. >>> >>> Some more segments, that I can't fully interprete are: >>> >>> Size Rss from - to Perm File 8852 7648 >>> 7f2818000000-7f28188a5000 rw-p 8940 6496 >>> 7f2814000000-7f28148bb000 rw-p 51116 4064 >>> 7f2835270000-7f283845b000 rw-p 2496 2048 >>> 7f2835000000-7f2835270000 rwxp 1788 1732 >>> 7f283d443000-7f283d602000 r--s .../lib/rt.jar 3304 1444 >>> 7f282c000000-7f282c33a000 rw-p 784 784 >>> 7f283f1d9000-7f283f29d000 rw-p .../lib/amd64/server/libjvm.so >>> 1564 648 3f6d200000-3f6d387000 r-xp /lib64/libc-2.12.so 536 524 >>> 7f2830000000-7f2830086000 rw-p 272 208 >>> 7f283f29d000-7f283f2e1000 rw-p >>> >>> and those nearly make up the "missing" 28MB Rss (whatever they >>> are). > > ... > >> But now, for the mere humans among us, what does it mean in terms >> of the OP and his original question : why does Tomcat 7 seem to >> be using 70 MB more memory at startup than Tomcat 6 ? Is it : - >> it doesn't matter. The numbers shown are wrong, and if you run >> 10 instances of Tomcat 7 at the same time, you will see that they >> are not really using 700 MB more than before. or - it is normal >> and expected. Tomcat 7 - because of the new Servlet Spec - needs >> to borogrove the watchamecalits, and this is using 70 MB more >> heap than before. In return, you get a 25% performance >> improvement later.. or - we have no clue. It does not happen on >> other machines, so there must be something special on your >> machine, and to find out what we need heap dumps. or - obviously >> some cleverer and definitive answer derived from Rainer's >> exhaustive analysis abobe, and which is ? ................ >> >> From the above analysis, I get the impression that there is only >> really a couple of MB additional memory used as one goes from >> Tomcat 6 to Tomcat 7 and then to Tomcat 8. > > Yes. Things might change if a real app comes into play. But again > I would not expect big differences if it is an app that only uses > old features, e.g. runs in old and new TC versions unchanged. The OP reported that be was using Tomcat's "examples" application. Presumably, he was using the appropriate "examples" application for each of the two Tomcats and not the same one in both. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJVEsKuAAoJEBzwKT+lPKRYPd8P/iF88kLLwsMkceRikX5FSTcV 9RkOm5X2OxmTvPL0F4nZBvBMls/9himcoj6jN5NPDnN9CnomJcOJG752ce0PbRLr +pv3/JxZtuUB/M66rx086IETw7z6+C0Fb4q0FM17M8i4oh8zSUhaYlO1KxH1MxkT Mwr7ePRjsAUHCRbExmajXIrnfAN48MGTgXIAx1g4nKvsdfkb1hWmzx4fRiObpM2y qrkc1CItBwgOAN5GLf+1xoBE/8QvX0Y+HqiwtNAMytgc4kJ5BmM2L+1zWX/w/QMv helpV4hZm0Frj0BrLQ2/OVmnBxzpvMC19gAsmC+MWLECpnL6tWgD3iUZ4ayWBooD RH+SMvXNmFgd9E53oNHy9reckFo8mV011pWxO5x8ru3PCGJPz17Jw0Q5HT+lZTsw pUqU0Iy+FnHJVbqHS0z1s2+7YW8YxUppZvZOpdBTW2UWUSsrLjkBKQ9zI08wNE5d 8fqG2vPGQmDwdX/hv3y61+rWpc5oDYq/772WjpNE21kheaeW6zQoGZtMqZxJt9lN GxtPsIihSbzGVG/JkAVMqMz4kpSXFRp/v2VSX/siZ0BY8lwE6sO/jcalMKpaFTlJ F+FLYA6xG000p7LvcxpcPRns3qX6flzxwuKNv4iCFA2woTHuPnPcvQqHAsv3w4Iz eLhl0r8suv2ygBbo6OOQ =UEZE -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
