posix_fallocate iterates over each page/block in a shmem to ensure the
OS allocates memory to back it. Large shmems will cause many read/write
calls to be made, and when profiling, it is very likely a SIGPROF signal
will interrupt us at sufficiently high sampling rates. Most attempts at
retrying will fail for the same reason, and this can cause the threads
to block for an indeterminate period of time.
To work around this we use the profiler's "thread sleep" mechanism to
indicate that the sampler thread should not interrupt this thread with
the sampling signal more than once.
Differential Revision: https://phabricator.services.mozilla.com/D87373
The goal of this patch is to reduce memory usage. On at least OSX, std::Queue
can use 4kb of memory even with nothing in it. This can be around 52kb of
memory per content process.
The segment size of 64 is fairly arbitrary, but these queues didn't have
more than a few hundred items in them, so it seemed like a reasonable
trade off between space for mostly-empty queues and segment overhead.
Differential Revision: https://phabricator.services.mozilla.com/D87325
An actual use of the `BACKGROUND_X11` thread may have briefly existed in
2009 but probably never shipped; it's been unused since then, and even
the comments mentioning it have been pruned (bug 909028, bug 624422).
The other thread types besides IO have been commented out ever since
they were first committed.
This patch also removes `x11_util.h`, which has been unused since 2017
(bug 1426284); earlier in history, it had one of those comments
mentioning the nonexistent X11 thread.
Differential Revision: https://phabricator.services.mozilla.com/D85346
The Chromium-derived IPC code was, as far as I can tell, originally
designed for Windows and assumed that channels would be named pipes,
managed and connected to via `std::wstring` paths. The port to Unix,
however, used unnamed `socketpair()` and passed them directly from
process to process, so it has no use for these channel IDs... but it
still computes and propagates them, even though they're not used, using
deprecated wide-string APIs.
This patch introduces a typedef for an abstract channel ID, which is a
`wstring` on Windows and an empty struct on Unix, to allow removing the
string code where it's not needed without needing to completely redesign
the channel abstraction.
Differential Revision: https://phabricator.services.mozilla.com/D72260
Chromium's fix for CVE-2011-3079 added an optional prefix parameter for
channel IDs, but we've never used it and have no plans to. (Chromium
itself doesn't appear to have used it except with the prefixes "gpu"
and "nacl", and the code has since been removed completely in favor of
Mojo.) So let's simplify things and remove it.
Differential Revision: https://phabricator.services.mozilla.com/D84276
This "create a pipe" operation has a mode where, on Unix, it doesn't
create a new transport but rather uses a hard-coded fd for the initial
IPC channel in a child process. (It was originally written for Windows
and the assumption of using named pipes and pathnames for everything.)
That seems like a footgun, so this patch checks for trying to "create"
that pipe twice. However, it doesn't check for accidentally calling it
in the parent process.
Differential Revision: https://phabricator.services.mozilla.com/D72259
The PipeMap class tries to simulate the Windows channel model (named
pipes that the client opens by a pathname) on Unix. However, it's
effectively dead code -- the map is empty except in some unit tests that
we never imported.
What we do is generate a "channel ID" with string formatting, then don't
pass it to the child or ever insert anything into the map, then the child
looks up an empty string and doesn't find it, so it uses the hard-coded
fixed fd for the initial channel.
Basically, it does nothing except maybe confuse unfamiliar readers, so
let's get rid of it.
Differential Revision: https://phabricator.services.mozilla.com/D72258
WebRender makes extensive use of shared memory buffers, particularly for
images decoded in the content process. These images can be arbitrarily
large, and there being insufficient memory for an allocation must be
handled gracefully.
On Linux, we will currently crash with a SIGBUS signal during image
decoding instead of just displaying the broken image tag. This is
because the pages backing the shared memory are only allocated when we
write to them. This blocks shipping WebRender on Linux.
This patch uses posix_fallocate to force the reservation of the pages,
and allows failing gracefully if they are unavailable.
Differential Revision: https://phabricator.services.mozilla.com/D80650
CVE-2018-4435 (https://crbug.com/project-zero/1671) was fixed in macOS
10.12 and up, but when we added uses of shm_open that would be affected
by it we still supported 10.9, so we added a workaround that tests for
the bug (by trying to exploit it) and falls back to the slower
alternative of temporary files if necessary.
The minimum supported version is now 10.12, and we've already
committed changes (e.g., to sandboxing) that would break the browser
on older versions, so we can remove this code. Note that we also have
cross-platform gtests that check for this type of bug, so we'll have some
warning if it's ever reintroduced.
Differential Revision: https://phabricator.services.mozilla.com/D83197
We'll never read more than MAX_DESCRIPTORS_PER_MESSAGE file descriptors in a
single message, so size the buffer based on that value.
Differential Revision: https://phabricator.services.mozilla.com/D79162
This adds 3 new profiler markers for each IPC message:
* One just before the first byte is sent over the IPC channel
* One just after the last byte is sent over the IPC channel
* One just after the last byte is received from the IPC channel
With the already-existing IPC markers (for when SendXXX and RecvXXX are
called), this allows us to calculate the following statistics:
* Send thread latency
* IPC send duration
* IPC recv latency
* Recv thread latency
For more information on how this is presented in the UI, see:
<https://github.com/firefox-devtools/profiler/pull/2535>.
Differential Revision: https://phabricator.services.mozilla.com/D70790
We want it to returning the actual nsThread if that's where the MessageLoop would dispatch its tasks; otherwise return the MessageLoop's EventTarget
Depends on D80357
Differential Revision: https://phabricator.services.mozilla.com/D80811
We want it to returning the actual nsThread if that's where the MessageLoop would dispatch its tasks; otherwise return the MessageLoop's EventTarget
Depends on D80357
Differential Revision: https://phabricator.services.mozilla.com/D80811
Gcc and Clang dumps gcda files just before an exec** or fork functions.
With ccov enabled, we can dump using a SIGUSR1 but if we're in the middle of dump (because of exec** or fork)
then a gcda file can stay locked and then another process can try to get a lock on it for ever.
So to avoid such a situation, we remove the SIGUSR1 handler just before the fork an set it back just after.
Differential Revision: https://phabricator.services.mozilla.com/D78051
This is more standard, and uses about 4kb less memory when almost empty,
which seems to be the common case in an idle content process. This should save
around 66kb per content process.
The next patch will get ride of this thin wrapper and use nsDataHashtable
directly.
Differential Revision: https://phabricator.services.mozilla.com/D76985
This method is the same as Put(), except that it asserts that the item
is not already present. It also puts the key second. Make it compatible
by hoisting out the assert and reversing the arguments. We can use the
definition of Put() defined in an earlier patch.
Differential Revision: https://phabricator.services.mozilla.com/D77167
nsTHashtable::Remove doesn't assert if the item isn't present. Match that
behavior by removing the assert and putting it at all of the call sites.
This just turns IDMap::Remove into RemoveIfPresent, so merge them.
Differential Revision: https://phabricator.services.mozilla.com/D77166
This function is similar to the Put() method in nsTHashtable, but it lists the
key second and it asserts that the key is not already in the map. This patch
swaps the arguments and hoists the assertion out, where appropriate. Note that
there are a few places that were working around this assert, so for those places
don't include the assert.
Differential Revision: https://phabricator.services.mozilla.com/D77165
This is more standard, and uses about 4kb less memory when almost empty,
which seems to be the common case in an idle content process. This should save
around 66kb per content process.
The next patch will get ride of this thin wrapper and use nsDataHashtable
directly.
Differential Revision: https://phabricator.services.mozilla.com/D76985
This method is the same as Put(), except that it asserts that the item
is not already present. It also puts the key second. Make it compatible
by hoisting out the assert and reversing the arguments. We can use the
definition of Put() defined in an earlier patch.
Differential Revision: https://phabricator.services.mozilla.com/D77167
nsTHashtable::Remove doesn't assert if the item isn't present. Match that
behavior by removing the assert and putting it at all of the call sites.
This just turns IDMap::Remove into RemoveIfPresent, so merge them.
Differential Revision: https://phabricator.services.mozilla.com/D77166
This function is similar to the Put() method in nsTHashtable, but it lists the
key second and it asserts that the key is not already in the map. This patch
swaps the arguments and hoists the assertion out, where appropriate. Note that
there are a few places that were working around this assert, so for those places
don't include the assert.
Differential Revision: https://phabricator.services.mozilla.com/D77165
Andrew Osmond
Andrew McCreight
Butkovits Atila
Jed Davis
Kashav Madan
Jim Porter
Jean-Yves Avenard
Brindusan Cristian
Sylvestre Ledru
Honza Bambas
Nika Layzell
Calixte Denizet
Csoregi Natalia