delta/go-git.git/src/runtime/pprof/runtime.go, branch dev.cmdgo github.com: golang/go runtime/pprof: expand final stack frame to avoid truncation 2020-03-05T21:51:02+00:00 Michael Pratt mpratt@google.com 2020-02-28T19:16:41+00:00 fadbf7404d2b1aca63993e289448fcc3b6a23107 When generating stacks, the runtime automatically expands inline functions to inline all inline frames in the stack. However, due to the stack size limit, the final frame may be truncated in the middle of several inline frames at the same location. As-is, we assume that the final frame is a normal function, and emit and cache a Location for it. If we later receive a complete stack frame, we will first use the cached Location for the inlined function and then generate a new Location for the "caller" frame, in violation of the pprof requirement to merge inlined functions into the same Location. As a result, we: 1. Nondeterministically may generate a profile with the different stacks combined or split, depending on which is encountered first. This is particularly problematic when performing a diff of profiles. 2. When split stacks are generated, we lose the inlining information. We avoid both of these problems by performing a second expansion of the last stack frame to recover additional inline frames that may have been lost. This expansion is a bit simpler than the one done by the runtime because we don't have to handle skipping, and we know that the last emitted frame is not an elided wrapper, since it by definition is already included in the stack. Fixes #37446 Change-Id: If3ca2af25b21d252cf457cc867dd932f107d4c61 Reviewed-on: https://go-review.googlesource.com/c/go/+/221577 Run-TryBot: Michael Pratt <mpratt@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Heschi Kreinick <heschi@google.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com> 
When generating stacks, the runtime automatically expands inline
functions to inline all inline frames in the stack. However, due to the
stack size limit, the final frame may be truncated in the middle of
several inline frames at the same location.

As-is, we assume that the final frame is a normal function, and emit and
cache a Location for it. If we later receive a complete stack frame, we
will first use the cached Location for the inlined function and then
generate a new Location for the "caller" frame, in violation of the
pprof requirement to merge inlined functions into the same Location.

As a result, we:

1. Nondeterministically may generate a profile with the different stacks
combined or split, depending on which is encountered first. This is
particularly problematic when performing a diff of profiles.

2. When split stacks are generated, we lose the inlining information.

We avoid both of these problems by performing a second expansion of the
last stack frame to recover additional inline frames that may have been
lost. This expansion is a bit simpler than the one done by the runtime
because we don't have to handle skipping, and we know that the last
emitted frame is not an elided wrapper, since it by definition is
already included in the stack.

Fixes #37446

Change-Id: If3ca2af25b21d252cf457cc867dd932f107d4c61
Reviewed-on: https://go-review.googlesource.com/c/go/+/221577
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
runtime/pprof: Mention goroutine label heritability 2019-08-07T14:40:17+00:00 David Finkel david.finkel@gmail.com 2019-07-31T13:10:28+00:00 0ca4f6be35d2abf54128b57c3aa1a1fcbd5adfe3 Document goroutine label inheritance. Goroutine labels are copied upon goroutine creation and there is a test enforcing this, but it was not mentioned in the docstrings for `Do` or `SetGoroutineLabels`. Add notes to both of those functions' docstrings so it's clear that one does not need to set labels as soon as a new goroutine is spawned if they want to propagate tags. Updates #32223 Updates #23458 Change-Id: Idfa33031af0104b884b03ca855ac82b98500c8b4 Reviewed-on: https://go-review.googlesource.com/c/go/+/189317 Reviewed-by: Ian Lance Taylor <iant@golang.org> 
Document goroutine label inheritance. Goroutine labels are copied upon
goroutine creation and there is a test enforcing this, but it was not
mentioned in the docstrings for `Do` or `SetGoroutineLabels`.

Add notes to both of those functions' docstrings so it's clear that one
does not need to set labels as soon as a new goroutine is spawned if
they want to propagate tags.

Updates #32223
Updates #23458

Change-Id: Idfa33031af0104b884b03ca855ac82b98500c8b4
Reviewed-on: https://go-review.googlesource.com/c/go/+/189317
Reviewed-by: Ian Lance Taylor <iant@golang.org>
runtime: add definitions for SetGoroutineLabels and Do 2017-02-06T20:29:37+00:00 Michael Matloob matloob@golang.org 2016-12-09T21:00:02+00:00 62956897c1743ee7e79895496180f84432f21d0a This change defines runtime/pprof.SetGoroutineLabels and runtime/pprof.Do, which are used to set profiler labels on goroutines. The change defines functions in the runtime for setting and getting profile labels, and sets and unsets profile labels when goroutines are created and deleted. The change also adds the package runtime/internal/proflabel, which defines the structure the runtime uses to store profile labels. Change-Id: I747a4400141f89b6e8160dab6aa94ca9f0d4c94d Reviewed-on: https://go-review.googlesource.com/34198 Run-TryBot: Michael Matloob <matloob@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Russ Cox <rsc@golang.org> Reviewed-on: https://go-review.googlesource.com/35010 
This change defines runtime/pprof.SetGoroutineLabels and runtime/pprof.Do, which
are used to set profiler labels on goroutines. The change defines functions
in the runtime for setting and getting profile labels, and sets and unsets
profile labels when goroutines are created and deleted. The change also adds
the package runtime/internal/proflabel, which defines the structure the runtime
uses to store profile labels.

Change-Id: I747a4400141f89b6e8160dab6aa94ca9f0d4c94d
Reviewed-on: https://go-review.googlesource.com/34198
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-on: https://go-review.googlesource.com/35010