On Thu, Aug 06, 2020 at 03:00:06PM -0000, Chris Lamb wrote: > Thanks for the heads-up; I don't subscribe to Redis bugs filed against > Ubuntu. So, for completeness, I can "reproduce" this in Debian:
Thanks for confirming, I was able to get the same behavior when I tried it on your latest Debian source package, hence why I felt reasonably comfortable it applied to both distributions. > I use the term "reproduce" in square quotes here because I am not > entirely sure why you are surprised by this error -- we deliberately > do not use the bundled version of jemalloc in Debian so we can use the > system one as per the general policy about avoiding embedded code > copies. I am curious: where did I say I was surprised by the behavior? I've used Debian (or Ubuntu derivatives) since about 1997 and I am aware of and strongly support the general policy. But at the same time, I wanted to be sure the community was made aware of it if they were setting up the service and expected the feature to work, and advise that at least a base config file comment about it could be a good idea if everybody decides not to fix it. > The only solutions would appear to be either (a) revert to using the > bundled jemalloc version (which would require a stronger case at this > point), or (b) ask upstream to merge this fragmentation support into > upstream jemalloc. I think this analysis is probably correct, depending on the estimated importance of the feature. If you could provide some advice, of the right way to temporarily disable the USE_SYSTEM_JEMALLOC patch, for building a one-off Debian package of the redis-server where defrag would be able to operate, probably that's good enough so that somebody would see it in the public historical record if they run into this later. > What am I missing here? I might be missing something ... I think you got it right. > I don't completely understand your remarks about the JEMALLOC_FRAG_HINT > define. Sorry, I was pretty tired when I wrote it, as I found it late in a 16 hour day of coding something else which had redis-server as a dependency, and took a break to debug it and report it in an effort to give back to the community at least a little bit, after I found it was apparently not seen before online in my search engine results. > Indeed, the code that surrounds it in zmalloc.h appears to > perfectly describe the trade-off being made: > > 73 /* We can enable the Redis defrag capabilities only if we are using > Jemalloc > 74 * and the version used is our special version modified for Redis having > 75 * the ability to return per-allocation fragmentation hints. */ > 76 #if defined(USE_JEMALLOC) && defined(JEMALLOC_FRAG_HINT) > 77 #define HAVE_DEFRAG > 78 #endif True, but that's a good few layers deep, so I was trying to give it a bit more exposure for the next user, whoever that might be. Thanks for your prompt reply and analysis, and for maintaining the package. Matthew.
