+Ulan Degenbaev <u...@google.com> On Thu, Sep 5, 2019 at 9:06 PM Philip Zeyliger <philip.zeyli...@airtable.com> wrote:
> Hi, > > I'm running into what seems to be a lot of v8 GC activity when piping a > 1GB file to /dev/null. The performance varies considerably depending on > whether or not I have an empty heap or one that I've filled to the tune of > 500MB. This is happening within node, but everything I can find is pointing > to some interaction between Node's IO and v8 garbage collection. > > My reproduction is at > https://gist.githubusercontent.com/philz/3e55a1a3377797d1fbc47b10a219ec6f/raw/1a6faadd60a0b920db08b39b759a2065bcd25831/slow.js; > running this with node will see the first 5 iterations happen more quickly > than the second 5 iterations. > > Looking at --trace_gc, both the "slow" and "fast" paths do ~80 mark-sweep > collections, but, when the heap is small, these take ~1-2ms whereas in the > slow case (bigger heap) they take ~200ms. > > Example slow: [2417:0x55f66b6913b0] 6858 ms: Mark-sweep 5.5 (11.0) -> > 4.3 (11.0) MB, 1.0 / 0.0 ms (+ 2.4 ms in 4 steps since start of marking, > biggest step 1.0 ms, walltime since start of marking 3 ms) finalize > incremental marking via task GC in old space requested > Example fast: [2417:0x55f66b6913b0] 35062 ms: Mark-sweep 770.9 (888.5) > -> 769.6 (888.5) MB, 2.8 / 0.0 ms (+ 224.0 ms in 247 steps since start of > marking, biggest step 3.3 ms, walltime since start of marking 227 ms) > finalize incremental marking via task GC in old space requested > > It's not surprising that mark-sweep takes longer on a bigger heap, but > it's reclaiming very little space, and I'd have expected it to either grow > the heap or use an incremental collector. > > I'd appreciate any suggestions you may have! (The real use case here > involves JSON.stringify() and uploading to S3 using the AWS SDK, but this > is the whittled down mystery.) > > Thanks, > > -- Philip > > -- > -- > v8-users mailing list > v8-users@googlegroups.com > http://groups.google.com/group/v8-users > --- > You received this message because you are subscribed to the Google Groups > "v8-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to v8-users+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/v8-users/c25cc22b-9c76-4657-bb45-927238bff613%40googlegroups.com > <https://groups.google.com/d/msgid/v8-users/c25cc22b-9c76-4657-bb45-927238bff613%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- -- v8-users mailing list v8-users@googlegroups.com http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to v8-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/v8-users/CAH3p7oOh3BZJE1RhBp-WGfF2L8AJ39fuR2BxeHeYY_HScyMAmA%40mail.gmail.com.
