Sigurd Meldgaard
2fe05bd568
This is a reland of commit b9b77058a9
Original change's description:
> Migrate to use pub workspace
>
> Use `pub get` to generate `.dart_tool/package_config.json` on gclient sync.
>
> All pkg/ (and a few third_party) packages that are developed inside the sdk repo are included in the workspace from the root `pubspec.yaml`.
>
> All dependencies that are pulled in via DEPS are added as path dependencies via `dependency_overrides` in the root `pubspec.yaml`.
>
> Bug: https://github.com/dart-lang/sdk/issues/56220
> Change-Id: I38c12b608c68da54c57821116cf9aa6696936746
> Tested: relies on CQ of existing tests. Should have no effect on functionality
> CoreLibraryReviewExempt: only core library change is adding a `// ignore:` comment. Should have no influence on functionality
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/397164
> Commit-Queue: Sigurd Meldgaard <sigurdm@google.com>
> Reviewed-by: Alexander Thomas <athom@google.com>
Bug: https://github.com/dart-lang/sdk/issues/56220
Change-Id: I29afabade2d2447dea05121cb87ff50bb21a4b76
Cq-Include-Trybots: luci.dart.try:flutter-linux-try,flutter-web-try
Tested: relies on CQ of existing tests. Should have no effect on functionality
CoreLibraryReviewExempt: only core library change is adding a `//
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/415561
Commit-Queue: Sigurd Meldgaard <sigurdm@google.com>
Reviewed-by: Alexander Thomas <athom@google.com>
Obtaining a heapsnapshot
There's several ways one can obtain a heapsnapshot
Obtain snapshot from live VM
One can use existing tools (e.g. observatory / DevTools) to load & save a heapsnapshot.
For convenience there's also a bin/download.dart script in
package:heapsnapshot that can be given an URL to a live VM and it will fetch a
heapsnapshot.
Programmatically
Note: enabled for debug and release Dart build modes, but not for product mode.
It's possible to programmatically dump a heapsnapshot to a file by using a
dart:developer API:
import 'dart:developer';
foo() {
...
// Will dump the heapsnapshot at a specific place in program execution.
// Allows very precise analysis of what data is live at a particular place.
NativeRuntime.writeHeapSnapshotToFile('dump.heapsnapshot');
...
}
CLI Usage:
Loading a snapshot
After launching bin/explore.dart one has to load a heapsnapshot before doing
anything else. This can be done with the load command. It will auto-complete
directories and any file with the .heapsnapshot extension.
# Load
load <file>
Finding all live objects
# Find all live objects by finding transitive closure of roots.
# We assign to a `all` variable for later usage.
all = closure roots
Show known sets of objects
# Show named sets / known variables
info
Show statistics of objects
To examine how many objects there are per class and how large they are one can
use the stats command:
stats all
Example usage session
# Filter lists from "all" into "lists"
lists = filter all _List
# Find empty lists into "empty-lists"
empty-lists = dfilter lists ==0
# Who's using the empty lists?
users empty-lists
# print that info (from $0 in this case as we didn't give it a name but it was
# the first one we didn't give a name)
stat $0
# Filter more
empty-growable-lists = filter (users empty-lists) _GrowableList
# Print
stats empty-growable-lists
# Who's using them?
retainers empty-growable-lists
# Look into strings next
strings = filter all String
# What's inside the strings
dstats strings
# Who's pointing to the big strings?
retainers (dfilter strings >=1024)
# Small strings
small-strings = dfilter strings <100
# See them
dstats small-strings
# Who's retaining the string "foo"
f = dfilter small-strings foo
retainters f
# Find stuff with specific field
hasField = filter all :specificField
stats closure hasField :specificField
foo = follow hasField :specificField
stats closure foo
# Stop the closure search if going into specific files
stats closure foo ^file1.dart ^file2.dart ^file3.dart