Sure, I just made quick fix to test my test case, and immediately share it with you. I will try to send more polite fix:) Regards lt 1 lis 2014 09:06 "Fergus Henderson" <fer...@google.com> napisał(a):
> Well, perhaps it would be a good idea to add a distccd flag or environment > variable to control the queue length rather than hard-coding 10 or 256? > On 31 Oct 2014 11:37, "Łukasz Tasz" <luk...@tasz.eu> wrote: > >> Hi Guys, >> >> I'm very very happy, reasons of my failures are identified. >> issue is in: >> --- src/srvnet.c (wersja 177) >> +++ src/srvnet.c (kopia robocza) >> @@ -99,7 +99,7 @@ >> rs_log_info("listening on %s", sa_buf ? sa_buf : "UNKNOWN"); >> free(sa_buf); >> >> - if (listen(fd, 10)) { >> + if (listen(fd, 256)) { >> rs_log_error("listen failed: %s", strerror(errno)); >> close(fd); >> return EXIT_BIND_FAILED; >> Index: src/io.c >> >> queue for new connetcion was minited to 10, that's why in case that >> cluster is overloaded, many connection are reseted. >> aim is to even wait 5 min for cluster availability, then compile localy. >> >> @Jarek, thanks for support! >> >> let's discuss if we should fix it or not. >> >> regards >> Lukasz >> >> >> Łukasz Tasz >> >> >> 2014-10-24 10:27 GMT+02:00 Łukasz Tasz <luk...@tasz.eu>: >> > Hi Martin >> > >> > What I have noticed. >> > Client tries to connect distccd 3 times with 500ms delays in between. >> > Linux kernel by default accept 128 connection. >> > If client creates connection, even if no executors are avaliable, >> > connection is accepted and queued by kernel running distccd. >> > This leads to situation that client thinks that distccd is reserved, >> > but in fact connection still waits to be accepted by distccd server. >> > I suspect that then client starts communication too fast, distcc wont >> > receive DIST token, and both sides waits, communication is broken, and >> > then timeouts are applied for client default is applied, for server >> > there is no defaults. >> > >> > fail scenarion is: >> > one distccd, and two distcc users, both of them will try to compile >> > with DISTCC_HOSTS=distccd/1,cpp,lzo, both users have lot of big >> > objects, cluster is overloaded with ratio 2. >> > This still should be OK, that third, and forth user will join cluster. >> > >> > Easy reproducer is to set one distcc, and set distcc_hosts=distccd/20, >> > this is broken configuration, but simulates overload by 20 - 20 >> > developers uses cluster in a same time. >> > Please remember that those are exceptional situation, but developer >> > can start compilation with -j 1000 from his laptop, and cluster will >> > timeout, then receiving 1000 jobs on a laptop will end with memmory >> > killer :D >> > Those are exceptional situation, and somehow cluster should handle that. >> > >> > In the attachement, next to some pump changes, you can find change >> > which is moving making connection to very beginning, when distcc is >> > picking host, also remote connection is made. if this will fail, discc >> > follow default behaviour, goes sleep for one sec, and will pick host >> > again. But this requires additional administration change on distccd >> > machine: >> > iptables -I INPUT -p tcp --dport 3632 -m connlimit --connlimit-above >> > <NUMBER OF DISTCCD> --connlimit-mask 0 -j REJECT --reject-with >> > tcp-reset >> > which accept only number of connection which equals to number of >> executors. >> > >> > So far so good! >> > remark, patch is done on top of arankine_distcc_issue16-r335, since >> > his pump changes are making pump mode working on my environment. >> > But distccd allocation I tested also on latest official distcc release. >> > >> > let me know what you think! >> > >> > with best regards >> > Lukasz >> > >> > >> > >> > Łukasz Tasz >> > >> > >> > 2014-10-24 2:42 GMT+02:00 Martin Pool <m...@sourcefrog.net>: >> >> It seems like if there's nowhere to execute the job, we want the client >> >> program to just pause, before using too many resources, until it gets >> >> unqueued by a server ready to do the job. (Or, by a local slot being >> >> available.) >> >> >> >> >> >> On Thu Oct 16 2014 at 2:43:35 AM Łukasz Tasz <luk...@tasz.eu> wrote: >> >>> >> >>> Hi Martin, >> >>> >> >>> Lets assume that you can trigger more compilation tasks executors >> then you >> >>> have. >> >>> In this scenario you are facing situation that cluster is saturated. >> >>> When such a compilation will be triggered by two developers, or two CI >> >>> (e.g jenkins) jobs, then cluster is saturated twice... >> >>> >> >>> Default behaviour is to lock locally slot, and try to connect three >> >>> times, if not, fallback, if fallback is disabled CI got failed build >> >>> (fallback is not the case, since local machine cannot handle -j >> >>> $(distcc -j)). >> >>> >> >>> consider scenario, I have 1000 objects, 500 executors, >> >>> - clean build on one machine takes >> >>> 1000 * 20 sec (one obj) = 20000 / 16 processors = 1000 sec, >> >>> - on cluster (1000/500) * 20 sec = 40 sec >> >>> >> >>> Saturating cluster was impossible without pump mode, but now with pump >> >>> mode after "warm up" effect, pump can dispatch many tasks, and I faced >> >>> situation that saturated cluster destroys almost every compilation. >> >>> >> >>> My expectation is that cluster wont reject my connect, or reject will >> >>> be handled, either by client, either by server. >> >>> >> >>> by server: >> >>> - accept every connetion, >> >>> - fork child if not accepted by child, >> >>> - in case of pump prepare local dir structure, receive headers >> >>> - --critical section starts here-- multi value semaphore with value >> >>> maxchild >> >>> - execute job >> >>> - release semaphore >> >>> >> >>> >> >>> Also what you suggested may be even better solution, since client will >> >>> pick first avaliable executor instead of entering queue, so distcc >> >>> could make connection already in function dcc_lock_one() >> >>> >> >>> I already tried to set DISTCC_DIR on a common nfs share, but in case >> >>> you are triggering so many jobs, this started to be bottle neck... I >> >>> won't tell about locking on nfs, and also scenario that somebody will >> >>> make a lock on nfs and machine will got crash - will not work by >> >>> design :) >> >>> >> >>> I know that scenario is not happening very often, and it has more or >> >>> less picks characteristic, but we should be happy that distcc cluster >> >>> is saturated and this case should be handled. >> >>> >> >>> hope it's more clear now! >> >>> br >> >>> LT >> >>> >> >>> >> >>> >> >>> >> >>> >> >>> >> >>> >> >>> >> >>> >> >>> Łukasz Tasz >> >>> >> >>> >> >>> 2014-10-16 1:39 GMT+02:00 Martin Pool <m...@sourcefrog.net>: >> >>> > Can you try to explain more clearly what difference in queueing >> behavior >> >>> > you >> >>> > expect from this change? >> >>> > >> >>> > I think probably the main change that's needed is for the client to >> ask >> >>> > all >> >>> > masters if they have space, to avoid needing to effectively poll by >> >>> > retrying, or getting stuck waiting for a particular server. >> >>> > >> >>> > On Wed, Oct 15, 2014 at 12:53 PM, Łukasz Tasz <luk...@tasz.eu> >> wrote: >> >>> >> >> >>> >> Hi Guys, >> >>> >> >> >>> >> please correct me if I'm wrong, >> >>> >> - currently distcc tries to connect server 3 times, with small >> delay, >> >>> >> - server forks x childs and all of them are trying to accept >> incoming >> >>> >> connection. >> >>> >> If server runs out of childs (all of them are busy), client will >> >>> >> fallback, and within next 60 sec will not try this machine. >> >>> >> >> >>> >> What do you think about redesigning distcc in a way that master >> server >> >>> >> will always accept inconing connection, fork a child, but in a same >> >>> >> time only x of them will be able to enter compilation >> >>> >> task(dcc_spawn_child)? (mayby preforking still could be used?) >> >>> >> >> >>> >> This may create kind of queue, client always can decide by his >> own, if >> >>> >> can wait some time, or maximum is DISTCC_IO_TIMEOUT, but still >> it's >> >>> >> faster to wait, since probably on a cluster side it's just a pick >> of >> >>> >> saturation then making falback to local machine. >> >>> >> >> >>> >> currently I'm facing situation that many jobs are making fallback, >> and >> >>> >> localmachine is being killed by make's -j calculated for distccd... >> >>> >> >> >>> >> other trick maybe to pick different machine, if current is busy, >> but >> >>> >> this may be much more complex in my opinion. >> >>> >> >> >>> >> what do you think? >> >>> >> regards >> >>> >> Łukasz Tasz >> >>> >> __ >> >>> >> distcc mailing list http://distcc.samba.org/ >> >>> >> To unsubscribe or change options: >> >>> >> https://lists.samba.org/mailman/listinfo/distcc >> >>> > >> >>> > >> >>> > >> >>> > >> >>> > -- >> >>> > Martin >> __ >> distcc mailing list http://distcc.samba.org/ >> To unsubscribe or change options: >> https://lists.samba.org/mailman/listinfo/distcc > >
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