I repeated the data loading with 32 G mem (instead of 11 G, see below). tdbloader2 showed a slight improvement:
tdbloader2 0:30 Data phase 5:45 Index phase Almost all of index phase (which seems to have taken longer with more memory - could have been caused by parallel activities on the vm cluster, however) was consumed by OS sort. Yet, tdbloader took off: tdbloader 0:30 Data phase 0:30 Index phase Excactly 59 min for the whole run! The rough figures of atop showed, near the end of the index phase, the tdbloader java process with 20.3 G rsize, 24.5 G vsize and 8 G vdata. Disk was under full load at this time, and about 9 G of temporary disk space (adding to the 18 G of the tdb dir) were used. Thank you very much for your help, Andy, and for this great piece of software. Joachim -----Ursprüngliche Nachricht----- Von: Neubert Joachim [mailto:j.neub...@zbw.eu] Gesendet: Freitag, 1. November 2013 13:43 An: users@jena.apache.org Betreff: AW: Declining TDB load performance with larger files I did a comparison of tdbloader vs. tdbloader2. The results are not relieable (machine-dependent, and perhaps even influenced by different background load on the vm cluster), but perhaps even then they may be interesting to others: tdbloader w/ 2G heap 4:15 Data phase 4:30 Index phase tdbloader2 w/ 2G heap 1:30 Data phase 6:30 Index phase So in sum tdbloader2 shows a slight advantage in my current configuration. The reduction of heap space had indeed brought an improvement: tdbloader w/ 10G heap 4:30 Data phase 5:45 Index phase Could I expect a larger improvement by adding more memory (for example upgrading from 11 to 32 GB)? Are there any experiences for estimating an optimal memory size for tdb loading? Cheers, Joachim -----Ursprüngliche Nachricht----- Von: Andy Seaborne [mailto:a...@apache.org] Gesendet: Montag, 28. Oktober 2013 16:58 An: users@jena.apache.org Betreff: Re: Declining TDB load performance with larger files Hi Joachim, What is happing is that the system is running out of working space and the disk is being used for real. > JAVA_OPTS: -d64 -Xms6g -Xmx10g Don't set -Xmx10g. Try a 2G heap. Don't bother with -Xms. More heap does not help - in fact, it can make it worse. TDB uses memory mapped files - these are not in Java heap space. The operating system manages how much real RAM is devoted to the virtual address space for the file. As your JVM grows, it is reducing the space for file caching. There is another effect. The OS is managing memory but sometimes it gets its policy wrong. Oddly, the faster the initial part of the load, the slower the speed drops off to when workspace RAM runs out. My guess is that the OS guesses some acecss style and then code then breaks that assumption. It can even different from run to run on the same machine. There is also tdbloader2 - it may be faster, it may not. It is vulnerable to OS in different ways. As it is so per-system specific, try each and see what happens, after fixing the heap issue. Andy On 28/10/13 12:01, Neubert Joachim wrote: > I'm loading a 111 million triples file (GND German Authority files). > For the first roughly 70 million triples, it's really fast (more than > 60,000 avg), but then throughput declines continuously to a thousand > or just some hundred triples (which brings down the avg to less than > 7000). During the last part of triples data phase, java is down to > 1-2% CPU usage, while disk usage goes up to 100%. > > As TDB writes to disk, I'd expect rather linear loading times. The > Centos 6 64bit machine (11.5 GB memory) runs on a VMware vSphere > cluster, with SAN hardware under-laying. As I observed the same > behavior at different times a day, with for sure different load > situations, there is no indication that it depended on parallel > actions on the cluster. > > Perhaps there is something wrong in my config, but I could not figure > out what it may be. I add an extract of the log below - it would be > great if somebody could help me with hints. > > Cheers, Joachim > > --------------- > > 2013-10-25 13:33:33 start run > > Configuration: > java version "1.6.0_24" > Java(TM) SE Runtime Environment (build 1.6.0_24-b07) > Java HotSpot(TM) > 64-Bit Server VM (build 19.1-b02, mixed mode) > JAVA_OPTS: -d64 -Xms6g > -Xmx10g > Jena: VERSION: 2.11.0 > Jena: BUILD_DATE: 2013-09-12T10:49:49+0100 > ARQ: VERSION: 2.11.0 > ARQ: BUILD_DATE: 2013-09-12T10:49:49+0100 > RIOT: VERSION: 2.11.0 > RIOT: BUILD_DATE: 2013-09-12T10:49:49+0100 > TDB: VERSION: 1.0.0 > TDB: BUILD_DATE: 2013-09-12T10:49:49+0100 > > Use fuseki tdb.tdbloader on file /opt/thes/var/gnd/latest/src/GND.ttl.gz > INFO -- Start triples data phase > INFO ** Load empty triples table > INFO Load: /opt/thes/var/gnd/latest/src/GND.ttl.gz -- 2013/10/25 13:33:35 MESZ > INFO Add: 10.000.000 triples (Batch: 64.766 / Avg: 59.984) > INFO Elapsed: 166,71 seconds [2013/10/25 13:36:21 MESZ] > INFO Add: 20.000.000 triples (Batch: 71.839 / Avg: 58.653) > INFO Elapsed: 340,99 seconds [2013/10/25 13:39:16 MESZ] > INFO Add: 30.000.000 triples (Batch: 67.750 / Avg: 60.271) > INFO Elapsed: 497,75 seconds [2013/10/25 13:41:52 MESZ] > INFO Add: 40.000.000 triples (Batch: 68.212 / Avg: 60.422) > INFO Elapsed: 662,01 seconds [2013/10/25 13:44:37 MESZ] > INFO Add: 50.000.000 triples (Batch: 54.171 / Avg: 60.645) > INFO Elapsed: 824,47 seconds [2013/10/25 13:47:19 MESZ] > INFO Add: 60.000.000 triples (Batch: 58.823 / Avg: 60.569) > INFO Elapsed: 990,60 seconds [2013/10/25 13:50:05 MESZ] > INFO Add: 70.000.000 triples (Batch: 45.495 / Avg: 60.468) > INFO Elapsed: 1.157,63 seconds [2013/10/25 13:52:52 MESZ] > INFO Add: 80.000.000 triples (Batch: 50.050 / Avg: 57.998) > INFO Elapsed: 1.379,36 seconds [2013/10/25 13:56:34 MESZ] > INFO Add: 90.000.000 triples (Batch: 13.954 / Avg: 52.447) > INFO Elapsed: 1.716,02 seconds [2013/10/25 14:02:11 MESZ] > INFO Add: 100.000.000 triples (Batch: 1.134 / Avg: 19.024) > INFO Elapsed: 5.256,29 seconds [2013/10/25 15:01:11 MESZ] > INFO Add: 110.000.000 triples (Batch: 944 / Avg: 7.643) > INFO Elapsed: 15.942,27 seconds [2013/10/25 17:59:17 MESZ] > INFO -- Finish triples data phase > INFO 111.813.447 triples loaded in 16.288,16 seconds [Rate: 6.864,71 per > second] > > Indexing phase also takes its time, and has some decrease in > performance too, but does not show a sharp drop. > > INFO -- Start triples index phase > INFO Elapsed: 20.563,36 seconds [2013/10/25 19:16:18 MESZ] > INFO ** Index SPO->POS: 111.786.233 slots indexed in 4.371,67 seconds > [Rate: 25.570,57 per second] > ... > INFO -- Finish triples index phase > INFO ** 111.786.233 triples indexed in 19.973,81 seconds [Rate: 5.596,64 per second] > INFO -- Finish triples load > INFO ** Completed: 111.813.447 triples loaded in 36.261,98 seconds [Rate: 3.083,49 per second] > >
