mirror of https://github.com/golang/go.git
cb133c6607
Currently we collect (add) all roots into a global array in a single-threaded GC phase. This hinders parallelism. With this change we just kick off parallel for for number_of_goroutines+5 iterations. Then parallel for callback decides whether it needs to scan stack of a goroutine scan data segment, scan finalizers, etc. This eliminates the single-threaded phase entirely. This requires to store all goroutines in an array instead of a linked list (to allow direct indexing). This CL also removes DebugScan functionality. It is broken because it uses unbounded stack, so it can not run on g0. When it was working, I've found it helpless for debugging issues because the two algorithms are too different now. This change would require updating the DebugScan, so it's simpler to just delete it. With 8 threads this change reduces GC pause by ~6%, while keeping cputime roughly the same. garbage-8 allocated 2987886 2989221 +0.04% allocs 62885 62887 +0.00% cputime 21286000 21272000 -0.07% gc-pause-one 26633247 24885421 -6.56% gc-pause-total 873570 811264 -7.13% rss 242089984 242515968 +0.18% sys-gc 13934336 13869056 -0.47% sys-heap 205062144 205062144 +0.00% sys-other 12628288 12628288 +0.00% sys-stack 11534336 11927552 +3.41% sys-total 243159104 243487040 +0.13% time 2809477 2740795 -2.44% R=golang-codereviews, rsc CC=cshapiro, golang-codereviews, khr https://golang.org/cl/46860043 |
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README
This is the source code repository for the Go programming language.
For documentation about how to install and use Go,
visit http://golang.org/ or load doc/install-source.html
in your web browser.
After installing Go, you can view a nicely formatted
doc/install-source.html by running godoc --http=:6060
and then visiting http://localhost:6060/doc/install/source.
Unless otherwise noted, the Go source files are distributed
under the BSD-style license found in the LICENSE file.
--
Binary Distribution Notes
If you have just untarred a binary Go distribution, you need to set
the environment variable $GOROOT to the full path of the go
directory (the one containing this README). You can omit the
variable if you unpack it into /usr/local/go, or if you rebuild
from sources by running all.bash (see doc/install.html).
You should also add the Go binary directory $GOROOT/bin
to your shell's path.
For example, if you extracted the tar file into $HOME/go, you might
put the following in your .profile:
export GOROOT=$HOME/go
export PATH=$PATH:$GOROOT/bin
See doc/install.html for more details.