Le jeu. 27 juin 2019 à 14:06, Jérôme Augé <[email protected]> a écrit :
> I have no "erl_crash.dump" neither, but I guess it's because the erlang > process is hard-killed by the kernel, and it does not have time for dumping > its state... > > @Adrien : what version of CouchDB are you using ? > Oops: just saw you are in 2.3.1. > > > Le jeu. 27 juin 2019 à 12:27, Adrien Vergé <[email protected]> a > écrit : > >> Vladimir, I would love to have your debugging skills and feedback on this, >> thanks for proposing! Unfortunately this only happens on real servers, >> after >> weeks of continuous real-life requests. In the past, we tried to reproduce >> it >> on test servers, but the memory leak doesn't happen if CouchDB is not very >> active (or it happens, but unnoticeable because too slowly). And these >> servers >> contain protected data that our rules don't allow us to share. >> >> I also searched for the crash dump (sudo find / -name '*.dump'; sudo find >> / >> -name 'erl_crash*') but couldn't find it; do you where it could be >> located? >> >> We already have swap on these machines. Next time the system comes close >> the >> OOM point, I will try to see whether they use swap or not. >> >> Le mer. 26 juin 2019 à 12:43, Vladimir Ralev <[email protected]> a >> écrit : >> >> > Ouch. I have an idea, can you add a bunch of swap on one of those >> machines, >> > say 20gigs, this should allow the machines to work for a little longer >> in >> > slow mode instead of running out of memory, which will buy you time to >> run >> > more diagnostics after the incident occurs. This will probably reduce >> the >> > response times a lot though and might break your apps. >> > >> > Also can you upload that erl_crash.dump file that the crash generated? >> > >> > PS I would love to get a shell access to a system like that, if you can >> > reproduce the issue on a test machine and give me access I should be >> able >> > to come up with something. Free of charge. >> > >> > On Wed, Jun 26, 2019 at 1:17 PM Adrien Vergé <[email protected]> >> > wrote: >> > >> > > Hi all, >> > > >> > > Here is more feedback, since one of our CouchDB servers crashed last >> > night. >> > > >> > > - Setup: CouchDB 2.3.1 on a 3-node cluster (q=2 n=3) with ~50k small >> > > databases. >> > > >> > > - Only one of the 3 nodes crashed. Others should crash in a few days >> > (they >> > > usually crash and restart every ~3 weeks). >> > > >> > > - update_lru_on_read = false >> > > >> > > - The extra memory consumption comes from beam.smp process (see graph >> > > below). >> > > >> > > - The crash is an OOM, see the last log lines before restart: >> > > >> > > eheap_alloc: Cannot allocate 2733560184 bytes of memory (of type >> > > "old_heap"). >> > > Crash dump is being written to: erl_crash.dump... >> > > [os_mon] memory supervisor port (memsup): Erlang has closed >> > > [os_mon] cpu supervisor port (cpu_sup): Erlang has closed >> > > >> > > - Over last weeks, beam.smp memory usage kept increasing and >> increasing. >> > > See >> > > the graph I made at >> https://framapic.org/jnHAyVEKq98k/kXCQv3pyUdz0.png >> > > >> > > - /_node/_local/_system metrics look normal. The difference between an >> > > "about >> > > to crash" node and a "freshly restarted and lots of free RAM" node, >> is >> > in >> > > uptime, memory.processes_used, memory.binary, context_switches, >> > > reductions, >> > > garbage_collection_count, io_input... as previously discussed with >> > Adam. >> > > >> > > - This command gives exactly the same output on an "about to crash" >> node, >> > > than >> > > on a "freshly restarted and lots of free RAM" node: >> > > >> > > MQSizes2 = lists:map(fun(A) -> {_,B} = case >> > > process_info(A,total_heap_size) >> > > of {XV,XB} -> {XV, XB}; _ERR -> io:format("~p",[_ERR]),{ok, 0} >> end, >> > > {B,A} >> > > end, processes()). >> > > >> > > Le jeu. 20 juin 2019 à 17:08, Jérôme Augé <[email protected]> a >> > > écrit : >> > > >> > > > We are going to plan an upgrade from 2.1.1 to 2.3.1 in the coming >> > weeks. >> > > > >> > > > I have a side question concerning CouchDB's upgrades: is the >> database >> > > > binary compatible between v2.1.1 and v2.3.1? In the case we ever >> need >> > to >> > > > downgrade back to 2.1.1, do the binary data can be kept? >> > > > >> > > > Regards, >> > > > Jérôme >> > > > >> > > > Le mer. 19 juin 2019 à 08:59, Jérôme Augé <[email protected]> >> a >> > > > écrit : >> > > > >> > > > > Thanks Adam for your explanations! >> > > > > >> > > > > The "update_lru_on_read" is already set to false on this instance >> (I >> > > had >> > > > > already seen the comments on these pull-requests). >> > > > > >> > > > > We are effectively running an "old" 2.1.1 version, and we have >> > advised >> > > > the >> > > > > client that an upgrade might be needed to sort out (or further >> > > > investigate) >> > > > > these problems. >> > > > > >> > > > > Thanks again, >> > > > > Jérôme >> > > > > >> > > > > >> > > > > >> > > > > Le mar. 18 juin 2019 à 18:59, Adam Kocoloski <[email protected]> >> a >> > > > > écrit : >> > > > > >> > > > >> Hi Jérôme, definitely useful. >> > > > >> >> > > > >> The “run_queue” is the number of Erlang processes in a runnable >> > state >> > > > >> that are not currently executing on a scheduler. When that value >> is >> > > > greater >> > > > >> than zero it means the node is hitting some compute limitations. >> > > Seeing >> > > > a >> > > > >> small positive value from time to time is no problem. >> > > > >> >> > > > >> Your last six snapshots show a message queue backlog in >> > couch_server. >> > > > >> That could be what caused the node to OOM. The couch_server >> process >> > > is a >> > > > >> singleton and if it accumulates a large message backlog there are >> > > > limited >> > > > >> backpressure or scaling mechanisms to help it recover. I noticed >> > > you’re >> > > > >> running 2.1.1; there were a couple of important enhancements to >> > reduce >> > > > the >> > > > >> message flow through couch_server in more recent releases: >> > > > >> >> > > > >> 2.2.0: https://github.com/apache/couchdb/pull/1118 < >> > > > >> https://github.com/apache/couchdb/pull/1118> >> > > > >> 2.3.1: https://github.com/apache/couchdb/pull/1593 < >> > > > >> https://github.com/apache/couchdb/pull/1593> >> > > > >> >> > > > >> The change in 2.2.0 is just a change in the default >> configuration; >> > you >> > > > >> can try applying it to your server by setting: >> > > > >> >> > > > >> [couchdb] >> > > > >> update_lru_on_read = false >> > > > >> >> > > > >> The changes in 2.3.1 offer additional benefits for couch_server >> > > message >> > > > >> throughput but you’ll need to upgrade to get them. >> > > > >> >> > > > >> Cheers, Adam >> > > > >> >> > > > >> P.S. II don’t know what’s going on with the negative memory.other >> > > value >> > > > >> there, it’s not intentionally meaningful :) >> > > > >> >> > > > >> >> > > > >> > On Jun 18, 2019, at 11:30 AM, Jérôme Augé < >> > [email protected]> >> > > > >> wrote: >> > > > >> > >> > > > >> > "beam.smp" just got killed by OOM, but I was not in front of >> the >> > > > >> machine to >> > > > >> > perform this command... >> > > > >> > >> > > > >> > However, here is the CouchDB log of "/_node/_local/_system" for >> > the >> > > 30 >> > > > >> > minutes preceding the OOM: >> > > > >> > - >> > > > >> > >> > > > >> >> > > > >> > > >> > >> https://gist.github.com/eguaj/1fba3eda4667a999fa691ff1902f04fc#file-log-couchdb-system-2019-06-18-log >> > > > >> > >> > > > >> > I guess the spike that triggers the OOM is so quick (< 1min) >> that >> > it >> > > > >> does >> > > > >> > not gets logged (I log every minute). >> > > > >> > >> > > > >> > Is there anything that can be used/deduced from the last line >> > logged >> > > > at >> > > > >> > 2019-06-18T16:00:14+0200? >> > > > >> > >> > > > >> > At 15:55:25, the "run_queue" is at 36: what does it means? >> Number >> > of >> > > > >> active >> > > > >> > concurrent requests? >> > > > >> > >> > > > >> > From 15:56 to 16:00 the "memory"."other" value is a negative >> > value: >> > > > >> does it >> > > > >> > means something special? or just an integer overflow? >> > > > >> > >> > > > >> > >> > > > >> > >> > > > >> > Le lun. 17 juin 2019 à 14:09, Vladimir Ralev < >> > > > [email protected]> >> > > > >> a >> > > > >> > écrit : >> > > > >> > >> > > > >> >> Alright, I think the issue will be more visible towards the >> OOM >> > > > point, >> > > > >> >> however for now since you have the system live with a leak, it >> > will >> > > > be >> > > > >> >> useful to repeat the same steps, but replace >> > > > >> >> "message_queue_len" with "total_heap_size" then with >> "heap_size" >> > > then >> > > > >> with >> > > > >> >> "stack_size" and then with "reductions". >> > > > >> >> >> > > > >> >> For example: >> > > > >> >> >> > > > >> >> MQSizes2 = lists:map(fun(A) -> {_,B} = case >> > > > >> process_info(A,total_heap_size) >> > > > >> >> of {XV,XB} -> {XV, XB}; _ERR -> io:format("~p",[_ERR]),{ok, 0} >> > end, >> > > > >> {B,A} >> > > > >> >> end, processes()). >> > > > >> >> >> > > > >> >> Then same with the other params. >> > > > >> >> >> > > > >> >> That can shed some light, otherwise someone will need to >> monitor >> > > > >> process >> > > > >> >> count and go into them by age and memory patterns. >> > > > >> >> >> > > > >> >> On Mon, Jun 17, 2019 at 2:55 PM Jérôme Augé < >> > > [email protected] >> > > > > >> > > > >> >> wrote: >> > > > >> >> >> > > > >> >>> The 2G consumption is from Adrien's system. >> > > > >> >>> >> > > > >> >>> On mine, since I setup the logging of "/_node/_local/_system" >> > > > output : >> > > > >> >>> - on june 14th max memory.processes was 2.6 GB >> > > > >> >>> - on june 15th max memory.processes was 4.7 GB >> > > > >> >>> - on june 16th max memory.processes was 7.0 GB >> > > > >> >>> - today (june 17th) max memory.processes was 8.0 GB (and >> with an >> > > > >> >>> interactive top I see spikes at 12 GB) >> > > > >> >>> >> > > > >> >>> The memory.processes seems to be steadily increasing over the >> > > days, >> > > > >> and >> > > > >> >> I'm >> > > > >> >>> soon expecting the out-of-memory condition to be triggered >> in a >> > > > >> couple of >> > > > >> >>> days. >> > > > >> >>> >> > > > >> >>> Le lun. 17 juin 2019 à 11:53, Vladimir Ralev < >> > > > >> [email protected]> >> > > > >> >> a >> > > > >> >>> écrit : >> > > > >> >>> >> > > > >> >>>> Nothing to see here, the message queue stat from Adam's >> advice >> > is >> > > > >> >>> accurate. >> > > > >> >>>> Note that you should run this only when there is already an >> > > > >> >> unreasonable >> > > > >> >>>> amount memory leaked/consumed. >> > > > >> >>>> >> > > > >> >>>> But now I realise you had "processes":1877591424 before >> restart >> > > > from >> > > > >> >> the >> > > > >> >>>> stats above which is less than 2G. Are you using only 2 >> gigs of >> > > > RAM? >> > > > >> I >> > > > >> >>> got >> > > > >> >>>> confused by the initial comment and I thought you had 15GB >> RAM. >> > > If >> > > > >> you >> > > > >> >>> are >> > > > >> >>>> only using 2 gigs of RAM, it's probably not enough for your >> > > > workload. >> > > > >> >>>> >> > > > >> >>>> On Mon, Jun 17, 2019 at 12:15 PM Jérôme Augé < >> > > > >> [email protected]> >> > > > >> >>>> wrote: >> > > > >> >>>> >> > > > >> >>>>> That command seems to work, and here is the output: >> > > > >> >>>>> >> > > > >> >>>>> --8<-- >> > > > >> >>>>> # /opt/couchdb/bin/remsh < debug.2.remsh >> > > > >> >>>>> Eshell V7.3 (abort with ^G) >> > > > >> >>>>> ([email protected])1> [{0,<0.0.0>}, >> > > > >> >>>>> {0,<0.3.0>}, >> > > > >> >>>>> {0,<0.6.0>}, >> > > > >> >>>>> {0,<0.7.0>}, >> > > > >> >>>>> {0,<0.9.0>}, >> > > > >> >>>>> {0,<0.10.0>}, >> > > > >> >>>>> {0,<0.11.0>}, >> > > > >> >>>>> {0,<0.12.0>}, >> > > > >> >>>>> {0,<0.14.0>}, >> > > > >> >>>>> {0,<0.15.0>}, >> > > > >> >>>>> {0,<0.16.0>}, >> > > > >> >>>>> {0,<0.17.0>}, >> > > > >> >>>>> {0,<0.18.0>}, >> > > > >> >>>>> {0,<0.19.0>}, >> > > > >> >>>>> {0,<0.20.0>}, >> > > > >> >>>>> {0,<0.21.0>}, >> > > > >> >>>>> {0,<0.22.0>}, >> > > > >> >>>>> {0,<0.23.0>}, >> > > > >> >>>>> {0,<0.24.0>}, >> > > > >> >>>>> {0,<0.25.0>}, >> > > > >> >>>>> {0,<0.26.0>}, >> > > > >> >>>>> {0,<0.27.0>}, >> > > > >> >>>>> {0,<0.28.0>}, >> > > > >> >>>>> {0,<0.29.0>}, >> > > > >> >>>>> {0,<0.31.0>}, >> > > > >> >>>>> {0,<0.32.0>}, >> > > > >> >>>>> {0,<0.33.0>}, >> > > > >> >>>>> {0,...}, >> > > > >> >>>>> {...}] >> > > > >> >>>>> ([email protected])2> {0,<0.38.0>} >> > > > >> >>>>> ([email protected])3> >> > > > [{current_function,{erl_eval,do_apply,6}}, >> > > > >> >>>>> {initial_call,{erlang,apply,2}}, >> > > > >> >>>>> {status,running}, >> > > > >> >>>>> {message_queue_len,0}, >> > > > >> >>>>> {messages,[]}, >> > > > >> >>>>> {links,[<0.32.0>]}, >> > > > >> >>>>> {dictionary,[]}, >> > > > >> >>>>> {trap_exit,false}, >> > > > >> >>>>> {error_handler,error_handler}, >> > > > >> >>>>> {priority,normal}, >> > > > >> >>>>> {group_leader,<0.31.0>}, >> > > > >> >>>>> {total_heap_size,5172}, >> > > > >> >>>>> {heap_size,2586}, >> > > > >> >>>>> {stack_size,24}, >> > > > >> >>>>> {reductions,24496}, >> > > > >> >>>>> {garbage_collection,[{min_bin_vheap_size,46422}, >> > > > >> >>>>> {min_heap_size,233}, >> > > > >> >>>>> {fullsweep_after,65535}, >> > > > >> >>>>> {minor_gcs,1}]}, >> > > > >> >>>>> {suspending,[]}] >> > > > >> >>>>> ([email protected])4> *** Terminating erlang (' >> > > > >> >> [email protected] >> > > > >> >>> ') >> > > > >> >>>>> -->8-- >> > > > >> >>>>> >> > > > >> >>>>> What should I be looking for in this output? >> > > > >> >>>>> >> > > > >> >>>>> Le ven. 14 juin 2019 à 17:30, Vladimir Ralev < >> > > > >> >> [email protected] >> > > > >> >>>> >> > > > >> >>>> a >> > > > >> >>>>> écrit : >> > > > >> >>>>> >> > > > >> >>>>>> That means your couch is creating and destroying processes >> > too >> > > > >> >>>> rapidly. I >> > > > >> >>>>>> haven't seen this, however I think Adam's message_queues >> stat >> > > > above >> > > > >> >>>> does >> > > > >> >>>>>> the same thing. I didn't notice you can get it from there. >> > > > >> >>>>>> >> > > > >> >>>>>> Either way it will be useful if you can get the shell to >> > work: >> > > > >> >>>>>> Try this command instead for the first, the rest will be >> the >> > > > same: >> > > > >> >>>>>> >> > > > >> >>>>>> MQSizes2 = lists:map(fun(A) -> {_,B} = case >> > > > >> >>>>>> process_info(A,message_queue_len) of {XV,XB} -> {XV, XB}; >> > _ERR >> > > -> >> > > > >> >>>>>> io:format("~p",[_ERR]),{ok, 0} end, {B,A} end, >> processes()). >> > > > >> >>>>>> >> > > > >> >>>>>> On Fri, Jun 14, 2019 at 5:52 PM Jérôme Augé < >> > > > >> >> [email protected] >> > > > >> >>>> >> > > > >> >>>>>> wrote: >> > > > >> >>>>>> >> > > > >> >>>>>>> I tried the following, but it seems to fail on the first >> > > > command: >> > > > >> >>>>>>> >> > > > >> >>>>>>> --8<-- >> > > > >> >>>>>>> # /opt/couchdb/bin/remsh >> > > > >> >>>>>>> Erlang/OTP 18 [erts-7.3] [source-d2a6d81] [64-bit] >> [smp:8:8] >> > > > >> >>>>>>> [async-threads:10] [hipe] [kernel-poll:false] >> > > > >> >>>>>>> >> > > > >> >>>>>>> Eshell V7.3 (abort with ^G) >> > > > >> >>>>>>> ([email protected])1> MQSizes2 = lists:map(fun(A) -> >> {_,B} >> > = >> > > > >> >>>>>>> process_info(A,message_queue_len), {B,A} end, >> processes()). >> > > > >> >>>>>>> ** exception error: no match of right hand side value >> > > undefined >> > > > >> >>>>>>> -->8-- >> > > > >> >>>>>>> >> > > > >> >>>>>>> >> > > > >> >>>>>>> Le ven. 14 juin 2019 à 16:08, Vladimir Ralev < >> > > > >> >>>> [email protected] >> > > > >> >>>>>> >> > > > >> >>>>>> a >> > > > >> >>>>>>> écrit : >> > > > >> >>>>>>> >> > > > >> >>>>>>>> Hey guys. I bet it's a mailbox leaking memory. I am very >> > > > >> >>> interested >> > > > >> >>>>> in >> > > > >> >>>>>>>> debugging issues like this too. >> > > > >> >>>>>>>> >> > > > >> >>>>>>>> I can suggest to get an erlang shell and run these >> commands >> > > to >> > > > >> >>> see >> > > > >> >>>>> the >> > > > >> >>>>>>> top >> > > > >> >>>>>>>> memory consuming processes >> > > > >> >>>>>>>> >> > > > >> >>> >> > > https://www.mail-archive.com/[email protected]/msg29365.html >> > > > >> >>>>>>>> >> > > > >> >>>>>>>> One issue I will be reporting soon is if one of your >> nodes >> > is >> > > > >> >>> down >> > > > >> >>>>> for >> > > > >> >>>>>>> some >> > > > >> >>>>>>>> amount of time, it seems like all databases >> independently >> > try >> > > > >> >> and >> > > > >> >>>>> retry >> > > > >> >>>>>>> to >> > > > >> >>>>>>>> query the missing node and fail, resulting in printing a >> > lot >> > > of >> > > > >> >>>> logs >> > > > >> >>>>>> for >> > > > >> >>>>>>>> each db which can overwhelm the logger process. If you >> > have a >> > > > >> >> lot >> > > > >> >>>> of >> > > > >> >>>>>> DBs >> > > > >> >>>>>>>> this makes the problem worse, but it doesn't happen >> right >> > > away >> > > > >> >>> for >> > > > >> >>>>> some >> > > > >> >>>>>>>> reason. >> > > > >> >>>>>>>> >> > > > >> >>>>>>>> On Fri, Jun 14, 2019 at 4:25 PM Adrien Vergé < >> > > > >> >>>>> [email protected] >> > > > >> >>>>>>> >> > > > >> >>>>>>>> wrote: >> > > > >> >>>>>>>> >> > > > >> >>>>>>>>> Hi Jérôme and Adam, >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> That's funny, because I'm investigating the exact same >> > > > >> >> problem >> > > > >> >>>>> these >> > > > >> >>>>>>>> days. >> > > > >> >>>>>>>>> We have a two CouchDB setups: >> > > > >> >>>>>>>>> - a one-node server (q=2 n=1) with 5000 databases >> > > > >> >>>>>>>>> - a 3-node cluster (q=2 n=3) with 50000 databases >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> ... and we are experiencing the problem on both setups. >> > > We've >> > > > >> >>>> been >> > > > >> >>>>>>> having >> > > > >> >>>>>>>>> this problem for at least 3-4 months. >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> We've monitored: >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> - The number of open files: it's relatively low (both >> the >> > > > >> >>>> system's >> > > > >> >>>>>>> total >> > > > >> >>>>>>>>> and or fds opened by beam.smp). >> > > > >> >>>>>>>>> https://framapic.org/wQUf4fLhNIm7/oa2VHZyyoPp9.png >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> - The usage of RAM, total used and used by beam.smp >> > > > >> >>>>>>>>> https://framapic.org/DBWIhX8ZS8FU/MxbS3BmO0WpX.png >> > > > >> >>>>>>>>> It continuously grows, with regular spikes, until >> killing >> > > > >> >>>> CouchDB >> > > > >> >>>>>>> with >> > > > >> >>>>>>>> an >> > > > >> >>>>>>>>> OOM. After restart, the RAM usage is nice and low, and >> no >> > > > >> >>> spikes. >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> - /_node/_local/_system metrics, before and after >> restart. >> > > > >> >>> Values >> > > > >> >>>>>> that >> > > > >> >>>>>>>>> significantly differ (before / after restart) are >> listed >> > > > >> >> here: >> > > > >> >>>>>>>>> - uptime (obviously ;-)) >> > > > >> >>>>>>>>> - memory.processes : + 3732 % >> > > > >> >>>>>>>>> - memory.processes_used : + 3735 % >> > > > >> >>>>>>>>> - memory.binary : + 17700 % >> > > > >> >>>>>>>>> - context_switches : + 17376 % >> > > > >> >>>>>>>>> - reductions : + 867832 % >> > > > >> >>>>>>>>> - garbage_collection_count : + 448248 % >> > > > >> >>>>>>>>> - words_reclaimed : + 112755 % >> > > > >> >>>>>>>>> - io_input : + 44226 % >> > > > >> >>>>>>>>> - io_output : + 157951 % >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> Before CouchDB restart: >> > > > >> >>>>>>>>> { >> > > > >> >>>>>>>>> "uptime":2712973, >> > > > >> >>>>>>>>> "memory":{ >> > > > >> >>>>>>>>> "other":7250289, >> > > > >> >>>>>>>>> "atom":512625, >> > > > >> >>>>>>>>> "atom_used":510002, >> > > > >> >>>>>>>>> "processes":1877591424, >> > > > >> >>>>>>>>> "processes_used":1877504920, >> > > > >> >>>>>>>>> "binary":177468848, >> > > > >> >>>>>>>>> "code":9653286, >> > > > >> >>>>>>>>> "ets":16012736 >> > > > >> >>>>>>>>> }, >> > > > >> >>>>>>>>> "run_queue":0, >> > > > >> >>>>>>>>> "ets_table_count":102, >> > > > >> >>>>>>>>> "context_switches":1621495509, >> > > > >> >>>>>>>>> "reductions":968705947589, >> > > > >> >>>>>>>>> "garbage_collection_count":331826928, >> > > > >> >>>>>>>>> "words_reclaimed":269964293572, >> > > > >> >>>>>>>>> "io_input":8812455, >> > > > >> >>>>>>>>> "io_output":20733066, >> > > > >> >>>>>>>>> ... >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> After CouchDB restart: >> > > > >> >>>>>>>>> { >> > > > >> >>>>>>>>> "uptime":206, >> > > > >> >>>>>>>>> "memory":{ >> > > > >> >>>>>>>>> "other":6907493, >> > > > >> >>>>>>>>> "atom":512625, >> > > > >> >>>>>>>>> "atom_used":497769, >> > > > >> >>>>>>>>> "processes":49001944, >> > > > >> >>>>>>>>> "processes_used":48963168, >> > > > >> >>>>>>>>> "binary":997032, >> > > > >> >>>>>>>>> "code":9233842, >> > > > >> >>>>>>>>> "ets":4779576 >> > > > >> >>>>>>>>> }, >> > > > >> >>>>>>>>> "run_queue":0, >> > > > >> >>>>>>>>> "ets_table_count":102, >> > > > >> >>>>>>>>> "context_switches":1015486, >> > > > >> >>>>>>>>> "reductions":111610788, >> > > > >> >>>>>>>>> "garbage_collection_count":74011, >> > > > >> >>>>>>>>> "words_reclaimed":239214127, >> > > > >> >>>>>>>>> "io_input":19881, >> > > > >> >>>>>>>>> "io_output":13118, >> > > > >> >>>>>>>>> ... >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> Adrien >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>> Le ven. 14 juin 2019 à 15:11, Jérôme Augé < >> > > > >> >>>> [email protected] >> > > > >> >>>>>> >> > > > >> >>>>>> a >> > > > >> >>>>>>>>> écrit : >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>>>> Ok, so I'll setup a cron job to journalize (every >> > minute?) >> > > > >> >>> the >> > > > >> >>>>>> output >> > > > >> >>>>>>>>> from >> > > > >> >>>>>>>>>> "/_node/_local/_system" and wait for the next OOM >> kill. >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>>> Any property from "_system" to look for in particular? >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>>> Here is a link to the memory usage graph: >> > > > >> >>>>>>>>>> https://framapic.org/IzcD4Y404hlr/06rm0Ji4TpKu.png >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>>> The memory usage varies, but the general trend is to >> go >> > up >> > > > >> >>> with >> > > > >> >>>>>> some >> > > > >> >>>>>>>>>> regularity over a week until we reach OOM. When >> > "beam.smp" >> > > > >> >> is >> > > > >> >>>>>> killed, >> > > > >> >>>>>>>>> it's >> > > > >> >>>>>>>>>> reported as consuming 15 GB (as seen in the kernel's >> OOM >> > > > >> >>> trace >> > > > >> >>>> in >> > > > >> >>>>>>>>> syslog). >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>>> Thanks, >> > > > >> >>>>>>>>>> Jérôme >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>>> Le ven. 14 juin 2019 à 13:48, Adam Kocoloski < >> > > > >> >>>>> [email protected]> >> > > > >> >>>>>> a >> > > > >> >>>>>>>>>> écrit : >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>>>> Hi Jérôme, >> > > > >> >>>>>>>>>>> >> > > > >> >>>>>>>>>>> Thanks for a well-written and detailed report (though >> > the >> > > > >> >>>>> mailing >> > > > >> >>>>>>>> list >> > > > >> >>>>>>>>>>> strips attachments). The _system endpoint provides a >> lot >> > > > >> >> of >> > > > >> >>>>>> useful >> > > > >> >>>>>>>> data >> > > > >> >>>>>>>>>> for >> > > > >> >>>>>>>>>>> debugging these kinds of situations; do you have a >> > > > >> >> snapshot >> > > > >> >>>> of >> > > > >> >>>>>> the >> > > > >> >>>>>>>>> output >> > > > >> >>>>>>>>>>> when the system was consuming a lot of memory? >> > > > >> >>>>>>>>>>> >> > > > >> >>>>>>>>>>> >> > > > >> >>>>>>>>>>> >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>> >> > > > >> >>>>>>> >> > > > >> >>>>>> >> > > > >> >>>>> >> > > > >> >>>> >> > > > >> >>> >> > > > >> >> >> > > > >> >> > > > >> > > >> > >> http://docs.couchdb.org/en/stable/api/server/common.html#node-node-name-system >> > > > >> >>>>>>>>>>> >> > > > >> >>>>>>>>>>> Adam >> > > > >> >>>>>>>>>>> >> > > > >> >>>>>>>>>>>> On Jun 14, 2019, at 5:44 AM, Jérôme Augé < >> > > > >> >>>>>>> [email protected]> >> > > > >> >>>>>>>>>>> wrote: >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> Hi, >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> I'm having a hard time figuring out the high memory >> > > > >> >> usage >> > > > >> >>>> of >> > > > >> >>>>> a >> > > > >> >>>>>>>>> CouchDB >> > > > >> >>>>>>>>>>> server. >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> What I'm observing is that the memory consumption >> from >> > > > >> >>> the >> > > > >> >>>>>>>> "beam.smp" >> > > > >> >>>>>>>>>>> process gradually rises until it triggers the >> kernel's >> > > > >> >> OOM >> > > > >> >>>>>>>>>> (Out-Of-Memory) >> > > > >> >>>>>>>>>>> which kill the "beam.smp" process. >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> It also seems that many databases are not compacted: >> > > > >> >> I've >> > > > >> >>>>> made >> > > > >> >>>>>> a >> > > > >> >>>>>>>>> script >> > > > >> >>>>>>>>>>> to iterate over the databases to compute de >> > fragmentation >> > > > >> >>>>> factor, >> > > > >> >>>>>>> and >> > > > >> >>>>>>>>> it >> > > > >> >>>>>>>>>>> seems I have around 2100 databases with a frag > 70%. >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> We have a single CouchDB v2.1.1server (configured >> with >> > > > >> >>> q=8 >> > > > >> >>>>> n=1) >> > > > >> >>>>>>> and >> > > > >> >>>>>>>>>>> around 2770 databases. >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> The server initially had 4 GB of RAM, and we are now >> > > > >> >> with >> > > > >> >>>> 16 >> > > > >> >>>>> GB >> > > > >> >>>>>>> w/ >> > > > >> >>>>>>>> 8 >> > > > >> >>>>>>>>>>> vCPU, and it still regularly reaches OOM. From the >> > > > >> >>>> monitoring I >> > > > >> >>>>>> see >> > > > >> >>>>>>>>> that >> > > > >> >>>>>>>>>>> with 16 GB the OOM is almost triggered once per week >> > > > >> >> (c.f. >> > > > >> >>>>>> attached >> > > > >> >>>>>>>>>> graph). >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> The memory usage seems to increase gradually until >> it >> > > > >> >>>> reaches >> > > > >> >>>>>>> OOM. >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> The Couch server is mostly used by web clients with >> the >> > > > >> >>>>> PouchDB >> > > > >> >>>>>>> JS >> > > > >> >>>>>>>>> API. >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> We have ~1300 distinct users and by monitoring the >> > > > >> >>>>> netstat/TCP >> > > > >> >>>>>>>>>>> established connections I guess we have around 100 >> > > > >> >>> (maximum) >> > > > >> >>>>>> users >> > > > >> >>>>>>> at >> > > > >> >>>>>>>>> any >> > > > >> >>>>>>>>>>> given time. From what I understanding of the >> > > > >> >> application's >> > > > >> >>>>> logic, >> > > > >> >>>>>>>> each >> > > > >> >>>>>>>>>> user >> > > > >> >>>>>>>>>>> access 2 private databases (read/write) + 1 common >> > > > >> >> database >> > > > >> >>>>>>>>> (read-only). >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> On-disk usage of CouchDB's data directory is around >> 40 >> > > > >> >>> GB. >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> Any ideas on what could cause such behavior >> (increasing >> > > > >> >>>>> memory >> > > > >> >>>>>>>> usage >> > > > >> >>>>>>>>>>> over the course of a week)? Or how to find what is >> > > > >> >>> happening >> > > > >> >>>>>> behind >> > > > >> >>>>>>>> the >> > > > >> >>>>>>>>>>> scene? >> > > > >> >>>>>>>>>>>> >> > > > >> >>>>>>>>>>>> Regards, >> > > > >> >>>>>>>>>>>> Jérôme >> > > > >> >>>>>>>>>>> >> > > > >> >>>>>>>>>> >> > > > >> >>>>>>>>> >> > > > >> >>>>>>>> >> > > > >> >>>>>>> >> > > > >> >>>>>> >> > > > >> >>>>> >> > > > >> >>>> >> > > > >> >>> >> > > > >> >> >> > > > >> >> > > > >> >> > > > >> > > >> > >> >
