This is the initial implementation of hot reload with multi-isolate
groups.
Implementation:
As before, when a service API call triggers a reload it will be routed
as an OOB message to a specific isolate (**). As opposed to before, that
isolate has now to coordinate with all other isolates, ensuring that it
"owns" the reload and all other isolates are waiting in a state that
allows reload.
This is implemented as a [ReloadOperationScope] which first participates
in other reloads (if there are any) and then owns the reload. It will
send a new kind of service message to all other registered isolates. All
of them have to check in before reload can proceed. If a new isolate
is about to join the group, it will participate when registering the
isolate. If an old isolate wants to die, it will participate when
unregistering the isolate.
This means that in addition to the existing StackOverFlow checks that
can process OOB messages and therefore reload, we'll have isolate
registration and unregistration as well as a new
Isolate::kCheckForReload OOB message handler where an isolate can
participate in a reload.
We consider the isolate group to be reloadable if the main isolate has
loaded the program and set the root library. Helper isolates don't need
to load any more kernel code and only initialize core libraries, so it's
fine to reload them during this time.
(**) The reason we continue to send reload service API calls to any
isolate in an isolate group is that re-loading might involve calling out
to the embedder's tag handler. Doing so currently requires an active
isolate.
If we allowed a subset of dart_api.h (the subset needed by the tag
handler) to be used only with an active IsolateGroup instead of an
active Isolate we could remove this requirement.
Edge cases:
There's various edge cases to consider: The main edge case is, we currently
maintain an upper limit to the number of isolates executing in parallel
(to ensure each can have big enough chunk of new space, i.e. TLAB).
If there are more isolates with active work they are waiting until one
of the exiting ones "yields". To ensure progress, if any such actively
running isolate gets a request to participate in a reload, it will mark
its own thread as "blocked" and therefore "yields", so another isolate
can make progress until all isolates are participating and the reload
can start.
Marking an isolate as "blocked" happens by exiting that isolate. It will
free up it's TLAB, decrease active mutator count and (if running on VM's
thread pool) also temporarily increase the thread pool size.
The side-effect of this is that it will use one pthread per isolate
during reload. In the future we can extend this first implementation, by
specially handling isolates that don't have a message handler running.
Doing so would require careful consideration to avoid races.
Testing:
In order to test this we use a small helper framework for reload tests.
The helper framework will, similar to real world reload e.g. in flutter,
will spawn a subprocess. It will use the service API to trigger reloads
in this subproces.
To synchronize between the reload driver and the application being
reloaded it allows watching for events to be printed to stdout/stderr.
The reload test itself can be written - similar to multitests - with
annotations such as `// @include-in-relload-0` in them. The testing
framework will then generate multiple application versions that all get
compiled to kernel.
For simplicity we generate the kernel using the standalone VM with
`--snapshot-kind=kernel` and avoid using the incremental compiler.
There are 4 different tests exercising different aspects of
multi-isolate reload:
vm/dart_2/isolates/reload_active_stack_test:
Performs a reload while a fixed number of isolates have an active
stack, thereby ensuring e.g. that all frames of all isolate mutator
stacks get deoptimized, ...
vm/dart_2/isolates/reload_no_active_stack_test:
Similar to the test above, but instead of having an active stack the
isolates can yield to the event loop, possibly be even descheduled
vm/dart_2/isolates/reload_many_isolates_test:
Similar to the test above, but this test uses many more isolates.
vm/dart_2/isolates/reload_many_isolates_live_and_die_test:
Performs a reload where isolates get spawned and die all the time.
There are always P isolates alive at any given point in time, each
of them spawns children when their parent has died.
Performing a reload catches isolates as various stages of their
lifecycle and can therefore cover a lot of corner cases.
TEST=vm/dart_2/isolates/reload_*_test.dart
Issue https://github.com/dart-lang/sdk/issues/36097
Change-Id: I97039b4084de040b7f2e22f5832a40d57ba398d5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/187461
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
This CL moves the [ProgramReloadContext] from [Isolate] to
[IsolateGroup] - since the program is shared across isolates. Amongst
other things, it also deoptimizes stacks of all isolate mutators.
There is still future work to do for hot-reloading multiple isolates
within a group, this is only the first change.
Issue https://github.com/dart-lang/sdk/issues/36097
TEST=Refactoring of existing implementation.
Change-Id: Ic394de265e3922f84657de2da25a46179b624647
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/183693
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
The logic for background compiler can be simplified due to:
* we only have one bg compiler
* it always optimizes
* it is allocated at isolate startup and freed on isolate shutdown
* an existing check in the compiler for whether the BG compiler is
disabled is racy and therefore not helpful
* when a mutator communicates with BG compiler it will use
SafepointMutexLocker instead of MutexLocker
This CL also ecapsulates disabling the BG compiler via a
NoBackgroundCompilerScope object. It allows nested disabling and guards
against races.
Issue https://github.com/dart-lang/sdk/issues/36097
TEST=Refactoring of existing code.
Change-Id: I36ed6592c9a8b91e94181698b7de662b4ee984e9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/183400
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Previously, deferred imports were really deferred, and the VM would have needed to trigger more loading as part of checking the validity of a reload and handle the re-entrancy of the tag handler and restart the checking a reload: all messy control flow that was side-stepped by just erroring-out. Currently, the language and kernel are incapable of truly deferred imports, so we need only propagate the state bit that checks loadLibrary was called and completed before members are accessed through the deferred prefix.
TEST=deferred_import_reload_test
Bug: https://github.com/dart-lang/sdk/issues/26878
Bug: https://github.com/flutter/flutter/issues/73602
Change-Id: I48bf3e8331630b732d96393e02b12f86de8cc5b5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/179620
Reviewed-by: Ben Konyi <bkonyi@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
This CL removes asserts that prevented background compiler from doing class finalization.
It adds program_lock synchronization for when object properties are updated during class finalization.
It also encloses code instructions installation into safepoint scopes to ensure that no code is executed during installation.
Issue https://github.com/dart-lang/sdk/issues/36097
TEST=existing test suite
Change-Id: If297e44f51b187242eca2cdcfff066c8f6386d97
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/178163
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
As part of making the compiler and other subsystems independent
of `Isolate` we have to move various state from `Isolate` to
`IsolateGroup` (or to another place).
Part of that is `Isolate::reload_context()`. In order to avoid name
conflict of what a `reload_context()` is, we separate it into
`reload_context()` and `program_reload_context()` where the former
contains GC information and the latter contains information about
changes in program structure.
Issue https://github.com/dart-lang/sdk/issues/36097
TEST=Pure refactoring - relying on existing test coverage.
Change-Id: I7e1b732ce8b34c8842718699d618be542bd59ff6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/177863
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Currently we have things called XPtr which are not what you get from ptr().
Old world:
handle->raw() returns RawObject* (tagged)
raw_obj->ptr() returns RawObject* (untagged)
After 6fe15f6df9:
handle->raw() returns ObjectPtr
obj_ptr->ptr() returns ObjectLayout*
New world:
handle->ptr() returns ObjectPtr
obj_ptr->untag() returns UntaggedObject*
TEST=ci
Change-Id: I6c7f34014cf20737607caaf84979838300d12df2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149367
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
As part of making the compiler and other subsystems independent
of `Isolate` we have to move various state from `Isolate` to
`IsolateGroup`.
The class_table and object_store were already moved to `IsolateGroup`.
This CL only replaces usages of `Isolate::{object_store,class_table}`
with the equivalent in `IsolateGroup`.
Issue https://github.com/dart-lang/sdk/issues/36097
TEST=Pure refactoring - relying on existing test coverage.
Change-Id: I34a0682d715b054d6c5faff077a513980f59a348
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/177126
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Attempts to run class finalizaton on background thread revealed the problem where during optimization(which could run on mutator thread too) we might need to finalize previously unseen class, load annotatons for it, load and set some constant fields. This could result in updating Fields guarded_cid, requires check during installation of newly produced optimized code. Because mutator thread is currently exempt from cloning and validating fields guards, that could result in invalid optimized code installation.
This CL ensures that fields are always cloned in optimizing compiler even when it runs on mutator thread.
Ability to run multiple optimizing compilers is also needed for dartbug.com/36097.
Issue https://github.com/dart-lang/sdk/issues/36097
TEST=existing test suite with ltw isolate groups enabled, https://dart-review.googlesource.com/c/sdk/+/176300 mocked up test(still to be improved).
Change-Id: I608f4abff30b468cb9d0ab270221a0ba72c32470
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/175341
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Remove the use of Fields, which have since the metadata mechanism was introduced come to require global registration.
Retain some sloppiness matching of declarations by name instead of identity for the sake of hot reload.
TEST=ci
Change-Id: Ifa4cc7724096c606f994b057b7838e124ceb3626
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/175141
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Previously the OOM would be delivered to the enclosing exit frame, bypassing the reload context properly tearing down. In particular, this meant the VM continued to use the class table saved on the reload context, which didn't contain classes finalized after the reload was aborted.
TEST=scavenger_abort
Bug: https://github.com/dart-lang/sdk/issues/43118
Change-Id: I96ad227dbd961cd5755ce0de0483d7d74b6667e2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/173142
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
This CL extends SubtypeTestCache entries with an additional slot that
contains the type being checked, to allow for future uses where
different runtime types can flow through a single checkpoint. This
change is separated from those future uses to determine the impact of
these changes only.
Thus, most SubtypeTestCache checks require the type as an additional
argument, and now the destination type register in TypeTestABI is now
untouched in SubtypeTestCache checks. Since there are currently no plans
for a dynamic InstanceOf test, the one argument SubtypeTestCache is left
unchanged.
Until we add cases in later CLs where the type can differ at the same
AssertAssignable instruction, we could check the type last since it is
currently guaranteed to be the same each time. However, we instead check
it after the instance, which is when it should be checked once we have
AssertAssignable instructions with types only known at runtime. This
avoids having to change it later, but also ensures the measured impact
of these changes can be compared to the impact of later changes.
In addition, this CL also unifies most of the code used by
GenerateInstanceOf (and also GenerateAssertAssignable via
GenerateInlineInstanceof on IA32). This is possible since register use
changes in the helper functions has eliminated the need to push the
instantiator and function type argument registers from TypeTestABI on
non-X64 architectures. By unifying these methods, we ensure that all
architectures appropriately set TypeTestABI::kDstTypeReg when necessary.
TEST=Existing tests on all architectures, change in object_test.cc.
Cq-Include-Trybots: luci.dart.try:vm-kernel-linux-debug-x64-try,vm-kernel-nnbd-linux-debug-x64-try,vm-kernel-linux-debug-ia32-try,vm-kernel-nnbd-linux-debug-ia32-try,vm-kernel-precomp-linux-debug-simarm_x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-nnbd-linux-debug-simarm_x64-try,vm-kernel-precomp-nnbd-linux-debug-x64-try,vm-kernel-linux-release-simarm-try,vm-kernel-linux-release-simarm64-try,vm-kernel-nnbd-linux-release-simarm-try,vm-kernel-nnbd-linux-release-simarm64-try,vm-kernel-precomp-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm64-try,vm-kernel-precomp-nnbd-linux-release-simarm64-try
Change-Id: I5d56de156e175758b3299ef1c776b848ac11f779
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/172503
Reviewed-by: Régis Crelier <regis@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Right now we assign class ids to top-level classes, abstract classes as
well as concrete classes. All of them have allocated from a 16-bit pool
of ids. The VM FATAL()s once it hits that limit.
Customers who run very large programs (significant amount of generated
code) on the Dart VM have started to hit this 16-bit class limit.
Concrete classes can have instances in the heap. Our current heap layout
only allows 16-bit class ids to be encoded in the header word. To avoid
increasing the size of heap objects or shrinking the size of the identity
hash code to 16-bit we keep class ids in object headers to be 16-bit.
Abstract classes cannot have instances in the heap. Though their class
ids are encoded in type objects. Furthermore we sort classes in
AOT/AppJIT mode to perform fast class-id range checks. To avoid impacting
this optimization we treat abstract classes the same way as concrete
classes.
Top-level classes cannot have instances in the heap. Their class ids are
only used in the runtime code, for example for hot-reload as well as
part of the service protocol.
=> We can allocate class ids outside the 16-bit range for top-level
classes, thereby freeing a significant amount of space in the 16-bit
range.
This CL does exactly that: We change classid_t to be int32_t. The
ClassLayout::id_ can now be assigned ids outside 16-bit range for
top-level classes. To do this we keep dart classes and top level classes
as separate arrays in the ClassTable.
Issue https://github.com/dart-lang/sdk/issues/42533
See also b/160229360
Change-Id: I6710a644e7b0ab2d4f4c792bef8e1f91cb117421
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153607
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Previous version
(landed via https://dart-review.googlesource.com/c/sdk/+/135683)
only worked if the dill was loaded via
Dart_LoadScriptFromKernel where script_kernel_size was set,
and when the platform dill could be loaded from a file called the right
thing.
This CL makes it work for Dart_LoadLibraryFromKernel too and allows
the VM to send the platform along (explicitly or implicitly) and only
tries to load the platform from a file with the right name if no
platform is given in any of the inputs.
This should fix http://b/148776866
Change-Id: I62317400a932b7dcd9e126a5a88907d507f9d658
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153609
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Jens Johansen <jensj@google.com>
This reverts commit 29e93bcdbd.
Reason for revert: Windows bots are failing with package resolution
errors. Looks like we are missing a windows path sanitization step.
Change-Id: Ib56f7e926b4f385fa3fde74c9c71947f64b8be1c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/151469
Reviewed-by: Siva Annamalai <asiva@google.com>
To avoid stopping all mutators when updating subtype test caches, we
ensure that any updates to the subtype test cache will be visible in a
consistent way to mutators by adding a store-release barrier when
updating the backing array of the STC.
Since STCs are always grown by allocating a new array with size+1, there
is no need to actually add barriers when accessing the individual
entries of the backing store.
To prevent multiple writers creating STCs and patching the pool or
updating a STC we add a mutex.
Issue https://github.com/dart-lang/sdk/issues/36097
Change-Id: Ic705619fe16772565ac11438fd15d3977cbb49c0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149164
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
Ryan Macnak