The compactor copies all live objects in old space to fresh pages, places forwarding pointers in the old objects, forwards all the pointers, then frees the old pages. This has a high space overhead. It is not meant for use in production, but meant to test that the VM is properly set up to handle old-space objects moving.
Large page objects and instruction objects are not moved.
Bug: https://github.com/dart-lang/sdk/issues/30978
Change-Id: Ia42683fd5e27a33702aa5e83bece803a8b005a4b
Reviewed-on: https://dart-review.googlesource.com/13624
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Zach Anderson <zra@google.com>
Reviewed-by: Erik Corry <erikcorry@google.com>
This reverts commit af251ddfec.
Reason for revert: Crashes on Windows.
Original change's description:
> [vm] Prefer stack bounds from the system thread library for overflow checks.
>
> Before this change, we would assume all stacks have the size the VM specifies for threads it creates, but this won't be accurate for the initial thread or threads created by the embedder.
>
> Change-Id: I6605a88d6666a6f9d47fbe047d3fdd02aa22c80a
> Reviewed-on: https://dart-review.googlesource.com/10209
> Reviewed-by: Zach Anderson <zra@google.com>
TBR=rmacnak@google.com,zra@google.com
Change-Id: I96eaccdc8edf6e3d319827a63d168534bad0518e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/13106
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Before this change, we would assume all stacks have the size the VM specifies for threads it creates, but this won't be accurate for the initial thread or threads created by the embedder.
Change-Id: I6605a88d6666a6f9d47fbe047d3fdd02aa22c80a
Reviewed-on: https://dart-review.googlesource.com/10209
Reviewed-by: Zach Anderson <zra@google.com>
In Flutter, the timeline buffer overflows much more quickly than the profile buffer, but usually timeline events are more helpful than profile ticks for understanding performance. This commit trades profile buffer space for timeline event space.
32-bit:
profile buffer: 12MB -> 6MB
timeline buffer: 0.5MB -> 2MB
Also increase the default sample depth to better handle Flutter's deep tree walks.
Change-Id: If092047fa89b2b3e57e57370bc435a591497b566
Reviewed-on: https://dart-review.googlesource.com/5903
Reviewed-by: Todd Turnidge <turnidge@google.com>
These samples are invalid and will cause an overflow later on when
generating the profiler report. Better to drop them early.
Closes#30788
Change-Id: I207251dde9de21a9c1e41fe763f878eb75352648
Reviewed-on: https://dart-review.googlesource.com/7781
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Todd Turnidge <turnidge@google.com>
Ensure we still start NativeSymbolResolver even if the profiler is off, since it is also used name weak handler finalizer functions and to produce stack traces for crashes.
R=bkonyi@google.com
Review-Url: https://codereview.chromium.org/2992893002 .
Note there is no option to disable the profiler. The profiler on Mac, Linux, and Android is based on SIGPROF, and there is no way to wait for all the outstanding signals as required to be able to safely free the sample buffer.
Saves ~20MB on 64-bit VMs.
R=cbernaschina@google.com, zra@google.com
Review-Url: https://codereview.chromium.org/2989093002 .
Inline instance object hash code into object header on 64 bit.
64 bit objects have 32 bits of free space in the header word.
This is used for the hash code in string objects. We take it
for the default hash code on all objects that don't override
the hashCode getter.
This is both faster and a memory reduction. Eg it makes the
MegaHashCode part of the Megamorphic benchmark 6 times faster.
This is a reland of https://codereview.chromium.org/2954453002/
which fixes an issue that made script snapshots generated on
64 bit platforms incompatible with 32 bit VMs.
BUG=
R=vegorov@google.com
Review-Url: https://codereview.chromium.org/2965723002 .
Inline instance object hash code into object header on 64 bit.
64 bit objects have 32 bits of free space in the header word.
This is used for the hash code in string objects. We take it
for the default hash code on all objects that don't override
the hashCode getter.
This is both faster and a memory reduction. Eg it makes the
MegaHashCode part of the Megamorphic benchmark 6 times faster.
This is a reland of https://codereview.chromium.org/2912863006/
It fixes issues with the 32 bit compare-swap instruction on
ARM64 and fixes a fragile tree shaking test that is sensitive
to which private methods are in the core libraries.
R=kustermann@google.com, vegorov@google.com
BUG=
Review-Url: https://codereview.chromium.org/2954453002 .
64 bit objects have 32 bits of free space in the header word.
This is used for the hash code in string objects. We take it
for the default hash code on all objects that don't override
the hashCode getter.
This is both faster and a memory reduction. Eg it shaves about
70% off the running time of this microbenchmark:
List list = [];
class Thing {
get hashCode => 42;
}
class Thing2 {
get hashCode => 42;
}
class Thing3 { }
class Thing4 { }
main() {
int sum = 103;
for (int i = 0; i < 10000000; i++) {
list = [];
list.add("foo");
list.add(123);
list.add(1.23);
list.add(new Object());
list.add(new Thing());
list.add(new Thing2());
list.add(new Thing3());
list.add(new Thing4());
for (int j = 0; j < 2; j++) {
sum ^= biz(list);
}
}
print(sum);
}
int biz(List list) {
int sum = 103;
for (var x in list) {
sum ^= x.hashCode;
}
return sum;
}
R=rmacnak@google.com, vegorov@google.com
BUG=
Review-Url: https://codereview.chromium.org/2912863006 .
The assertions which tried to assert that we only use
StackFrameIterator to walk frames of the current thread was incorrect.
We already have cases where other threads will walk the stack of the
mutator thread, see below for an example where this can happen.
Thread::VisitObjectPointers was incorrectly passing Thread::Current() to
the StackFrameIterator instead of 'this'. (Code in thread_registry.cc will
loop over a number of threads and calls VisitObjectPointers on them)
Mutator thread:
0 pthread_cond_wait@@GLIBC_2.3.2
1 dart::Monitor::WaitMicros
2 dart::Monitor::Wait
3 dart::MonitorLocker::Wait
4 dart::ThreadBarrier::Sync
5 dart::GCMarker::MarkObjects
6 dart::PageSpace::MarkSweep
7 dart::Heap::CollectOldSpaceGarbage
8 dart::Heap::CollectNewSpaceGarbage
9 dart::Heap::CollectGarbage
10 dart::DN_HelperObject_<native>
11 dart::BootstrapNatives::<native>
<dart frames>
MarkTask thread:
1 dart::EntryFrame::VisitObjectPointers
2 dart::Thread::VisitObjectPointers <---- Walks mutator thread stack
3 dart::ThreadRegistry::VisitObjectPointers <---- Iterates over a number of threads
4 dart::Isolate::VisitStackPointers
5 dart::Isolate::VisitObjectPointers
6 dart::GCMarker::IterateRoots
7 dart::MarkTask::Run
8 dart::ThreadPool::Worker::Loop
9 dart::ThreadPool::Worker::Main
10 dart::ThreadStart
R=rmacnak@google.com
Review-Url: https://codereview.chromium.org/2845053003 .
Like HOST_ARCH_*, HOST_OS_* describes the OS the VM is running on, which may be different from the OS the VM is generating code for during AOT compilation.
Currently we conflate the two when emitting AOT as assembly, and we get away with it because Flutter only uses assembly for targeting iOS and one can only target iOS from a Mac, but we expect to use assembly for Android as well so native tools can unwind Dart frames.
R=zra@google.com
Review-Url: https://codereview.chromium.org/2750843003 .
Revert "Revert "Fixed issue in MallocHooks where a MallocHookScope was accidentally removed during a merge, causing a deadlock in the hooks. Also turned off stack trace collection in a test that was timing out as a result of the stack trace collection.""
This reverts commit 1a5b555aa9.
BUG=
R=zra@google.com
Review-Url: https://codereview.chromium.org/2711353003 .
Currently it relies on OSThread::stack_base_ which is explicitly set.
However if we encounter a crash or assertion failure early we don't have stack_base_ set yet.
This CL allows us to get correct stack dump even if OSThread::stack_base_ is not set yet by falling back to low-level APIs:
* On Linux and Android we fallback to pthread_attr_getstack
* On Mac OS X we use pthread_get_stackaddr_np/pthread_get_stacksize_np.
* On Windows we read limits from TIB.
This code is mostly a port of the battle tested thread limits code from Oilpan GC inside Blink. The only differences is that we don't fallback to __libc_stack_end for the main thread.
We also cleanup GetAndValidateIsolateStackBounds a bit to avoid duplication there.
(This change is motivated by https://github.com/dart-lang/sdk/issues/28692 where crash in bootstrapping does not produce any useful stack trace)
BUG=
R=johnmccutchan@google.com
Review-Url: https://codereview.chromium.org/2680123004 .
Install a signal handler in the standalone VM that dumps a backtrace
similar to what we already do on assertion failures.
For now only Linux and MacOS are supported.
BUG=
R=asiva@google.com
Review URL: https://codereview.chromium.org/2514113002 .
Ryan Macnak