Yes, definitely OOME. My friend Eric crashed Accumulo again and we saw this in tserver_localhost.out:
# # java.lang.OutOfMemoryError: Java heap space # -XX:OnOutOfMemoryError="kill -9 %p" # Executing /bin/sh -c "kill -9 12833"... On Thu, Apr 2, 2015 at 11:49 PM, Dylan Hutchison <[email protected]> wrote: > I think it is an OOME. Here's the debug log file, showing a clear descend > from 189MB free to 52kB free memory before manually restarting the tserver > 4 minutes later. Looks like I lost the .err files for now; would need to > reproduce the crash to get them again. > > 2015-03-26 08:34:01,242 [tserver.TabletServer] DEBUG: gc > ParNew=26.24(+0.01) secs ConcurrentMarkSweep=0.13(+0.00) secs* > freemem=189,300,488(-330,224) *totalmem=259,522,560 > 2015-03-26 08:34:01,549 [tserver.TabletServer] DEBUG: ScanSess tid > 127.0.0.1:55823 6r 374,161 entries in 2.98 secs, nbTimes = [1 69 3.27 > 375] > 2015-03-26 08:34:01,842 [Audit ] INFO : operation: permitted; user: > root; client: 127.0.0.1:55823; > 2015-03-26 08:34:01,842 [Audit ] INFO : operation: permitted; user: > root; client: 127.0.0.1:55823; > 2015-03-26 08:34:01,844 [tserver.TabletServer] DEBUG: ScanSess tid > 127.0.0.1:55823 !0 5 entries in 0.00 secs, nbTimes = [1 1 1.00 1] > 2015-03-26 08:34:03,034 [tserver.TabletServer] DEBUG: Got getScans message > from user: !SYSTEM > 2015-03-26 08:34:03,091 [tserver.TabletServer] DEBUG: MultiScanSess > 127.0.0.1:38998 2 entries in 0.00 secs (lookup_time:0.00 secs tablets:1 > ranges:1) > 2015-03-26 08:34:04,507 [tserver.TabletServer] DEBUG: gc > ParNew=26.38(+0.14) secs ConcurrentMarkSweep=0.99(+0.86) secs > *freemem=44,246,264(-145,384,448) > *totalmem=259,522,560 > 2015-03-26 08:34:05,963 [tserver.TabletServer] DEBUG: ScanSess tid > 127.0.0.1:55017 !0 0 entries in 0.00 secs, nbTimes = [2 2 2.00 1] > 2015-03-26 08:34:05,966 [tserver.TabletServer] DEBUG: gc > ParNew=26.38(+0.00) secs ConcurrentMarkSweep=2.25(+1.26) secs > *freemem=6,657,016(-182,973,696) > *totalmem=259,522,560 > 2015-03-26 08:34:07,549 [tserver.TabletServer] DEBUG: gc > ParNew=26.38(+0.00) secs ConcurrentMarkSweep=3.73(+1.48) secs > *freemem=439,152(-189,191,560) > *totalmem=259,522,560 > 2015-03-26 08:34:08,284 [tserver.TabletServer] DEBUG: Got getScans message > from user: !SYSTEM > *2015-03-26 08:34:10,469 [tserver.TabletServer] WARN : Running low on > memory* > 2015-03-26 08:34:10,470 [tserver.TabletServer] DEBUG: gc > ParNew=26.38(+0.00) secs ConcurrentMarkSweep=6.63(+2.90) secs > *freemem=52,816(-189,577,896) > *totalmem=259,522,560 > 2015-03-26 08:34:14,623 [tserver.TabletServer] DEBUG: Got getScans message > from user: !SYSTEM > 2015-03-26 08:34:17,382 [tserver.TabletServer] DEBUG: ScanSess tid > 127.0.0.1:55017 !0 0 entries in 5.04 secs, nbTimes = [4,972 4,972 > 4,972.00 1] > 2015-03-26 08:34:24,674 [tserver.TabletServer] DEBUG: Got getScans message > from user: !SYSTEM > 2015-03-26 08:34:35,716 [cache.LruBlockCache] DEBUG: Cache Stats: Sizes: > Total=23.286858MB (24418040), Free=6.7131424MB (7039240), Max=30.0MB > (31457280), Counts: Blocks=7750, Access=125628, Hit=102578, Miss=23050, > Evictions=25, Evicted=15299, Ratios: Hit Ratio=81.65218234062195%, Miss > Ratio=18.34782063961029%, Evicted/Run=611.9600219726562, Duplicate Reads=1 > *2015-03-26 08:38:37,256 [server.Accumulo] INFO : tserver starting* > > > > > > On Thu, Apr 2, 2015 at 6:34 PM, Josh Elser <[email protected]> wrote: > >> That seems perfectly reasonable to me, IMO. I'm surprised to hear the >> tserver crashed. >> >> Taking a quick glance at the code, it looks like this would be a good >> place to do some optimization in the BatchScanner's impl >> (TabletServerBatchReaderImpl). The BatchScanner will bin the ranges to the >> tablets and the servers hosting those tablets. Normally, this would be >> spread out, but, in your single server case, all 1M rows would all go to a >> single TabletServer in one RPC call. >> >> I'm guessing a good optimization here would be to check the size of a >> batch of Ranges for a single tabletserver, and when above a certain >> threshold, split the batch in half and try to reprocess each half (the >> recursion would naturally keep splitting until we get down to some >> high-watermark). >> >> Point being, if your client VM constructed the Ranges without issue, the >> BatchScanner impl should be smart enough to not knock over a TabletServer. >> >> What was the reason the tserver died? OOME? Was there anything at the end >> of the log files or in the .out/.err files? >> >> - Josh >> >> >> Dylan Hutchison wrote: >> >>> A friend of mine has a use case where he wants to scan ~1M individual >>> rows, scattered across a ~15GB table. He performed the following: >>> >>> 1. Gather a List of Range objects, each one a singleton range spanning >>> an entire row. >>> 2. Create a BatchScanner with one read thread. >>> 3. Set the ranges via BatchScanner.setRanges() >>> 4. Start iterating through the scanner. >>> >>> Performing these steps crashed the TabletServer for my friend (haven't >>> had time to verify it myself yet). We're using a single-node standalone >>> 1.6.1 Accumulo instance. >>> >>> Is this a bad way to use Accumulo? I advised my friend to batch the >>> reads into groups of ~10k ranges and see if that helps. I wanted to >>> check with the community and see if we're doing something weird. If the >>> behavior should have worked, I can try to put together a test case >>> reproducing it, that creates a table with many entries and then scans >>> with many ranges. >>> >>> Thanks, >>> Dylan Hutchison >>> >>> >
