837846 - mach should respect MOZ_MAKE_FLAGS

Status: RESOLVED FIXED

(Firefox Build System :: General, defect)

Description

[Marco Bonardo [:mak]]

I have 8 cores (4 physical, 4 logical), on my Windows box -j12 is quite faster than -j8, so I have MOZ_MAKE_FLAGS="-j12" set, though mach ignores it and builds with -j8

Comment 1

[Gregory Szorc [:gps]]

This is with |mach build <target>| since that uses a slightly different dispatch path from |mach build|.

Comment 2

[Jan Keromnes [:janx]]

Either `mach` ignores the jobs flag or it limits the number to 8 jobs. I confirm that running `./mach build -j100` seems to only ever use 8 threads.

Comment 3

[Gregory Szorc [:gps]]

How are you setting MOZ_MAKE_FLAGS? You need to be using |mk_add_options MOZ_MAKE_FLAGS| in your mozconfig.

Are you sure that mozconfig is the one loaded by mach?

Comment 4

[Jan Keromnes [:janx]]

I am not using mozconfig, but `./mach help build` says:

    --jobs jobs, -j jobs  Number of concurrent jobs to run. Default is the number of CPUs.

Comment 5

[Dan Mosedale (:dmosedale, :dmose)]

I see this too, and it's frustrating, because it slows my machine to a crawl when compiling.

mk_add_options MOZ_MAKE_FLAGS="-s"

is in my $(SRCDIR)/.mozconfig.

How do I verify that that's the .mozconfig in use?

Comment 6

[Jared Wein [:jaws] (please needinfo? me)]

(In reply to Dan Mosedale (:dmose) - not reading bugmail; needinfo? for response from comment #5)
> I see this too, and it's frustrating, because it slows my machine to a crawl
> when compiling.
> 
> mk_add_options MOZ_MAKE_FLAGS="-s"
> 
> is in my $(SRCDIR)/.mozconfig.
> 
> How do I verify that that's the .mozconfig in use?

cat obj-dir/.mozconfig should show what .mozconfig was used.

Comment 7

[Dan Mosedale (:dmosedale, :dmose)]

gps: i just verified that this problem does indeed occur even using mk_add_options as described above, and that the mozconfig that has that is definitely in use in the build that displays the behavior.

Comment 8

[Mike Hommey [:glandium]]

(In reply to Dan Mosedale (:dmose) - not reading bugmail; needinfo? for response from comment #5)
> I see this too, and it's frustrating, because it slows my machine to a crawl
> when compiling.
> 
> mk_add_options MOZ_MAKE_FLAGS="-s"
> 
> is in my $(SRCDIR)/.mozconfig.
> 
> How do I verify that that's the .mozconfig in use?

mach defaults to -s, so what is your problem exactly?

Comment 9

[Dan Mosedale (:dmosedale, :dmose)]

glandium: the fact that i'm not specifying -j at all, and it's compiling with -j8, which eats all my cores.

Comment 10

[Mike Hommey [:glandium]]

(In reply to Dan Mosedale (:dmose) - not reading bugmail; needinfo? for response from comment #9)
> glandium: the fact that i'm not specifying -j at all, and it's compiling
> with -j8, which eats all my cores.

The default for mach is to use all cores. If you want only one core to be used, you need to explicitely add -j1. Either in MOZ_MAKE_FLAGS or on mach command line.

Comment 11

[Mike Hommey [:glandium]]

BTW, reading when this bug was filed, I'm sure the code handling MOZ_MAKE_FLAGS has been changed after this bug was filed, so it should be checked whether this still applies or not. It's also not clear what this bug is about (mach build or mach build foo).

Comment 12

[Dan Mosedale (:dmosedale, :dmose)]

glandium: sorry, I should have been more communicative.  I tried a whole bunch of things, and that was where I ended up.

I just did a clobber, switched back to using

mk_add_options MOZ_MAKE_FLAGS="-j1" 

and verified that that change propagated through to my objdir.

Despite this, -j8 is not being overridden (I can see it ps), and all 8 cores are being used.

Comment 13

[Dan Mosedale (:dmosedale, :dmose)]

And in my cases, this is just executing "mach build".

Comment 14

[Mike Hommey [:glandium]]

(In reply to Dan Mosedale (:dmose) - not reading bugmail; needinfo? for response from comment #12)
> glandium: sorry, I should have been more communicative.  I tried a whole
> bunch of things, and that was where I ended up.
> 
> I just did a clobber, switched back to using
> 
> mk_add_options MOZ_MAKE_FLAGS="-j1" 
> 
> and verified that that change propagated through to my objdir.
> 
> Despite this, -j8 is not being overridden (I can see it ps), and all 8 cores
> are being used.

So, I can confirm this, and this is fallout from bug 762358, which landed a couple months ago, so is unrelated to the original bug. So, this bug currently exists, but has nothing to do with why it was originally filed.

Comment 15

[Mike Hommey [:glandium]]

Attachment: Fix MOZ_MAKE_FLAGS handling for client.mk

After bug 762358 mk_add_options MOZ_MAKE_FLAGS was simply ignored in client.mk
processing. At the same time, mach environment was expecting a list of options
while the mozconfig reader returned a single string, so straighten this up at
the same time.

Comment 16

[Marco Bonardo [:mak]]

For sure ./mach build <target> doesn't respect my -j12... that said, if it is respected for ./mach build I'm happy enough.

Comment 17

[Dan Mosedale (:dmosedale, :dmose)]

Thanks much for the quick patch, Mike!

Comment 18

[Michael Shal [:mshal]]

Comment on attachment 8493544 [details] [diff] [review]
Fix MOZ_MAKE_FLAGS handling for client.mk

This looks fine, though it doesn't seem to apply to './mach build foo' - was your intention to fix that as well? Just a './mach build' works now though.

Comment 19

[Mike Hommey [:glandium]]

mach build foo is a different beast. It needs a separate fix.

Comment 20

[Mike Hommey [:glandium]]

Attachment: Respect MOZ_MAKE_FLAGS when running make commands from mach

This addresses the issue for make commands that don't go through client.mk.

Comment 21

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/07130f61fbe0

Comment 22

[Michael Shal [:mshal]]

Comment on attachment 8494180 [details] [diff] [review]
Respect MOZ_MAKE_FLAGS when running make commands from mach

Seems fine, though note it doesn't work if you just use MOZ_MAKE_FLAGS=-j (ie: unlimited jobs). I don't know if we really care to support that, though.

Comment 23

[Mike Hommey [:glandium]]

(In reply to Michael Shal [:mshal] from comment #22)
> Comment on attachment 8494180 [details] [diff] [review]
> Respect MOZ_MAKE_FLAGS when running make commands from mach
> 
> Seems fine, though note it doesn't work if you just use MOZ_MAKE_FLAGS=-j
> (ie: unlimited jobs). I don't know if we really care to support that, though.

I think it's actually a good feature that -j is ignored. However, the following option shouldn't be eaten. I'll fix this.

Comment 24

[Mike Hommey [:glandium]]

Attachment: Respect MOZ_MAKE_FLAGS when running make commands from mach

Comment 25

[Mike Hommey [:glandium]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/72e22f3d7cc6

Comment 26

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/72e22f3d7cc6

Comment 27

[Ryan VanderMeulen [:RyanVM]]

I suppose this change is what broke my local build.

mk_add_options MOZ_MAKE_FLAGS="-s -j 12"

Leads to:
4:22.03 mozmake.EXE[2]: *** No rule to make target '12'.  Stop.

On a fresh clobber.

Comment 28

[Ryan VanderMeulen [:RyanVM]]

Confirmed that I can build again with rev 72e22f3d7cc6 backed out.

Comment 29

[Mike Hommey [:glandium]]

It's a consequence of client.mk not supporting spaces between -j and 12 when setting MOZ_PARALLEL_BUILD, which predates this bug, but that this bug unhides, because now mach almost always sets MOZ_PARALLEL_BUILD. It also means before this bug, the build would have failed if you ran e.g. mach build -j8. Please file a separate bug.