*: force zone.o to link on macOS#15275
*: force zone.o to link on macOS#15275tamird merged 1 commit intocockroachdb:masterfrom tamird:fix-jemalloc-mac-again
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This change is |
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I wonder why this didn't bite us with c-jemalloc, because Go also builds a static library out of each package, right? Also, I feel obligated to ask: you verified this actually works, yeah? |
pkg/cli/start_jemalloc.go
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| // #cgo CPPFLAGS: -DJEMALLOC_NO_DEMANGLE | ||
| // #cgo LDFLAGS: -ljemalloc | ||
| // #cgo !darwin LDFLAGS: -ljemalloc | ||
| // #cgo darwin LDFLAGS: -ljemalloc -u_je_zone_register |
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Do you have to do this in all of the cgo directives? I would think this one would be sufficient.
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Yes, one is sufficient, but do you think the inconsistency is worth it?
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Inconsistency doesn't bother me. I would have only made this change to server/status/runtime_jemalloc.go because that is the only one we care about. Also, add a comment explaining what is going on.
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What do you mean? The problem here is not a reporting problem; before this change, jemalloc is not being used in our macOS builds, period.
Added a comment.
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before this change, jemalloc is not being used in our macOS builds, period.
Do we care other than the stats reporting? Btw, given that this is the second time this has broken, perhaps a small test is in order.
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Hm, this behaviour is specific to macOS, which we don't run CI on. How would we test it?
I think we care, even in the absence of stats reporting, but probably just for consistency with other platforms.
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Hm, this behaviour is specific to macOS, which we don't run CI on. How would we test it?
Developers run tests on macOS frequently. A test would have caught this very quickly. Also, seems possible for this to break on another platform as well.
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PS I don't particularly care how many places you add -u_je_zone_register. The test is the more important bit.
tamird
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I wonder why this didn't bite us with c-jemalloc, because Go also builds a static library out of each package, right?
It's because cgo mashes all the object files into a single object file called _all.o before creating the static archive; the linker is only able to omit whole files, not single functions, so it is forced to keep everything.
Also, I feel obligated to ask: you verified this actually works, yeah?
Yes.
pkg/cli/start_jemalloc.go
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| // #cgo CPPFLAGS: -DJEMALLOC_NO_DEMANGLE | ||
| // #cgo LDFLAGS: -ljemalloc | ||
| // #cgo !darwin LDFLAGS: -ljemalloc | ||
| // #cgo darwin LDFLAGS: -ljemalloc -u_je_zone_register |
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Yes, one is sufficient, but do you think the inconsistency is worth it?
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| // Used to force allocation in tests. | ||
| func allocateMemory() { |
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Why not put this in the test file?
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Because `import "C"` is not supported in tests. Can't make this stuff up.
…On Apr 22, 2017 22:11, "Nikhil Benesch" ***@***.***> wrote:
***@***.**** commented on this pull request.
------------------------------
In pkg/server/status/runtime_jemalloc.go
<#15275 (comment)>
:
> @@ -120,3 +126,9 @@ func getJemallocStats(ctx context.Context) (uint, uint, error) {
return uint(js.Allocated), uint(js.Resident), nil
}
+
+// Used to force allocation in tests.
+func allocateMemory() {
Why not put this in the test file?
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This is the mechanism by which jemalloc hooks into `malloc` on macOS; without it, jemalloc is not used. Closes #15272.
This is the mechanism by which jemalloc hooks into
mallocon macOS;without it, jemalloc is not used.
Closes #15272.