[DONOTMERGE] Revert "Put off major collections to improve GC times."

[Keno]

As far as I can tell, win32 CI started failing with OOM after this PR. Putting up the revert to investigate whether it is indeed the root cause.

Reverts #44215

[chflood]

Aw man.. I didn't test on win32. If this is the problem I can come up with a less aggressive heuristic for 32bit builds.

[DilumAluthge]

So, it looks like tester_win32 is no longer out-of-memorying, but it is failing with some Profile failure.

@IanButterworth Any idea why Profile is failing? I keep retrying the job, but the test failure keeps happening.

[IanButterworth]

I don't see an error?

[Keno]

See e.g. https://build.julialang.org/#/builders/42/builds/3478/steps/5/logs/stdio. Probably the first thing to do is to change the test to print out what the output was on failure, so we can see if it's something dumb.

[IanButterworth]

This design fix might help #44639

Otherwise, I don't think there's been a recent change on windows profiling

[IanButterworth]

#44639 tester_win32 didn't get OOM-ed and failed with the same error, so it seems neither PR are fixes?

[Keno]

The OOM error is somewhat intermittent. It would be good to fix the Profile error if we can to get a cleaner signal on the OOM.

[IanButterworth]

I added some debug logs to #44639 the subprocess is either taking ages or frozen and gets killed by the watchdog.

      From worker 4:	KILLING BY PROFILE TEST WATCHDOG
      From worker 4:	
      From worker 4:	120.057066 seconds (6.76 k allocations: 268.992 KiB, 0.07% compilation time)
      From worker 4:	  0.000782 seconds (19 allocations: 544 bytes)
      From worker 4:	s = ""
      From worker 4:	read(p, String) = ""

so this test appears to be going really slow on win32

using Profile
f(::Val) = GC.safepoint()
@profile for i = 1:10^3; f(Val(i)); end
print(Profile.len_data())

[DilumAluthge]

Should we have a Sys.iswindows, and either reduce the number of iterations on Windows (so that the test takes less time to run), or just skip that test entirely on Windows?

[IanButterworth]

More debug in #44639

The profile test just passed and the subprocess took 20s. On MacOS it takes ~3s, on my Windows VM with 32-bit julia it takes 10s. When it fails it means it's being killed after 120s, which seems like a big deviation from normal CI behavior.

Also, that run got OOM-ed.

Could it be that too many parallel test processes are being run on the win32 machine?