mirror of
https://github.com/chromium/crashpad.git
synced 2025-03-10 06:36:02 +00:00
460943dd9a
The DoubleForkAndExec() function was taking over 622 milliseconds to run
on macOS 11 (BigSur) on Intel i5-1038NG7. I did some debugging by adding
some custom traces and found that the fork() syscall is the bottleneck
here, i.e., the first fork() takes around 359 milliseconds and the
nested fork() takes around 263 milliseconds. Replacing the nested fork()
and exec() with posix_spawn() reduces the time consumption to 257
milliseconds!
See https://github.com/libuv/libuv/pull/3064 to know why fork() is so
slow on macOS and why posix_spawn() is a better replacement.
Another point to note is that even base::LaunchProcess() from Chromium
calls posix_spawnp() on macOS -
8f8d82dea0:base/process/launch_mac.cc;l=295-296
Change-Id: I25c6ee9629a1ae5d0c32b361b56a1ce0b4b0fd26
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/3641386
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
72 lines
3.6 KiB
C++
72 lines
3.6 KiB
C++
// Copyright 2017 The Crashpad Authors. All rights reserved.
|
||
//
|
||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||
// you may not use this file except in compliance with the License.
|
||
// You may obtain a copy of the License at
|
||
//
|
||
// http://www.apache.org/licenses/LICENSE-2.0
|
||
//
|
||
// Unless required by applicable law or agreed to in writing, software
|
||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
// See the License for the specific language governing permissions and
|
||
// limitations under the License.
|
||
|
||
#ifndef CRASHPAD_UTIL_POSIX_FORK_AND_SPAWN_H_
|
||
#define CRASHPAD_UTIL_POSIX_FORK_AND_SPAWN_H_
|
||
|
||
#include <string>
|
||
#include <vector>
|
||
|
||
namespace crashpad {
|
||
|
||
//! \brief Executes a (grand-)child process.
|
||
//!
|
||
//! The grandchild process will be started through the
|
||
//! `fork()`-and-`posix_spawn()` pattern. This allows the grandchild to fully
|
||
//! disassociate from the parent. The grandchild will not be a member of the
|
||
//! parent’s process group or session and will not have a controlling terminal,
|
||
//! providing isolation from signals not intended for it. The grandchild’s
|
||
//! parent process, in terms of the process tree hierarchy, will be the process
|
||
//! with process ID 1, relieving any other process of the responsibility to reap
|
||
//! it via `waitpid()`. Aside from the three file descriptors associated with
|
||
//! the standard input/output streams and any file descriptor passed in \a
|
||
//! preserve_fd, the grandchild will not inherit any file descriptors from the
|
||
//! parent process.
|
||
//!
|
||
//! \param[in] argv The argument vector to start the grandchild process with.
|
||
//! `argv[0]` is used as the path to the executable.
|
||
//! \param[in] envp A vector of environment variables of the form `var=value` to
|
||
//! be passed to `posix_spawn()`. If this value is `nullptr`, the current
|
||
//! environment is used.
|
||
//! \param[in] preserve_fd A file descriptor to be inherited by the grandchild
|
||
//! process. This file descriptor is inherited in addition to the three file
|
||
//! descriptors associated with the standard input/output streams. Use `-1`
|
||
//! if no additional file descriptors are to be inherited.
|
||
//! \param[in] use_path Whether to consult the `PATH` environment variable when
|
||
//! requested to start an executable at a non-absolute path. If `false`,
|
||
//! `posix_spawn()`, which does not consult `PATH`, will be used. If `true`,
|
||
//! `posix_spawnp()`, which does consult `PATH`, will be used.
|
||
//! \param[in] child_function If not `nullptr`, this function will be called in
|
||
//! the intermediate child process, prior to the `posix_spawn()`. Take note
|
||
//! that this function will run in the context of a forked process, and must
|
||
//! be safe for that purpose.
|
||
//!
|
||
//! \return `true` on success, and `false` on failure with a message logged.
|
||
//! Only failures that occur in the parent process that indicate a definite
|
||
//! failure to start the the grandchild are reported in the return value.
|
||
//! Failures in the intermediate child or grandchild processes cannot be
|
||
//! reported in the return value, and are addressed by logging a message and
|
||
//! terminating. The caller assumes the responsibility for detecting such
|
||
//! failures, for example, by observing a failure to perform a successful
|
||
//! handshake with the grandchild process.
|
||
bool ForkAndSpawn(const std::vector<std::string>& argv,
|
||
const std::vector<std::string>* envp,
|
||
int preserve_fd,
|
||
bool use_path,
|
||
void (*child_function)());
|
||
|
||
} // namespace crashpad
|
||
|
||
#endif // CRASHPAD_UTIL_POSIX_FORK_AND_SPAWN_H_
|