Hi Kristian, On Mon, Nov 17, 2014 at 10:58:52AM +0100, Kristian Nielsen wrote: ...skip...
> > me> Strange... Monty should have fixed this. Error monitor thread should > > call > > me> log_get_lsn_nowait(), which basically does trylock. Do you happen to > > have call > > me> trace? > > > me> According to history ACQUIRE -> RELEASE fix appeared in 10.0.13 and fix > > for > > me> log_get_lsn() appeared in 10.0.14. Both fixes appeared similtaneously > > in 5.5.40. > > me> > > > Stating that this patch fixes run-time hangs that I'm not aware of is kind > > of > > strange. > > > > So I repeat my question: Are there any other known hangs? > > Well, there are no hangs that we "know" is caused by this bug. There are hangs > that we suspect could be caused by this bug. > > Monty's patch, as you say, is not in 10.0.13. And it is insufficient, Jan > apparently changed another mutex lock to be trylock, which is not in 10.0.14 > or 5.5.40, IIUC. There might be other ways for the error monitor thread to get > stuck, and even if not there can still be a server stall for 1 second. > > I think you already know all of this, so I'm not sure what answer you are > looking for from me, sorry... Ok, that's exactly what I was looking for. Now I see that there are other mutexes acquired by the error monitor thread. And this is a potential for other hangs. Thanks for clarifications! > > > Could you suggest better wording for cset comment? > > Here is a suggestion: > > "In MariaDB 5.5.40 and 10.0.13, the InnoDB/XtraDB low-level mutex > implementation was inadvertently broken, so that a waiter may miss the wakeup > when another thread releases the mutex. This affects at least x86 and amd64 > architectures. This could result in threads occasionally stalling for about 1 > second, or in some cases even hanging the whole server infinitely." Ok, this sounds good. Thanks, Sergey _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
