parallel stop-the-world garbage collection

I cleaned up the remaining code from my go-gc fork
and integrated it into the current Go tree.  It still
stops the world during garbage collection but if there
are extra procs lying around idle, it will use them
(up to GOMAXPROCS) to parallelize both the mark
and the sweep phases.

There is a CL at http://codereview.appspot.com/4641082.
It is not ready for review, and it only runs on linux/amd64
because that is the only platform I bothered to implement
usleep on.

One thing I've noticed is that while programs do get a
little faster, the total user time increases by much more
than the saved real time.  Even making the busy loops
give up and do timed sleeps after the first few iterations
doesn't help - it's not spinning that is the problem, but
there is a problem.  For example, the test/bench/parser
program has these times when I vary the number of
cores the collector can use on a 16-core machine:

1 38.0u 38.8r
2 44.6u 35.2r
3 47.8u 32.8r
4 56.6u 33.6r
5 53.9u 33.0r
6 51.0u 32.0r
7 53.9u 33.4r
8 54.0u 32.9r

Re: parallel stop-the-world garbage collection

Re: code review 4532093: goinstall: add support patch-tag.com (issue4532093)

*** Abandoned ***

http://codereview.appspot.com/4532093/

Re: code review 4642049: goinstall: documentation for new remote repository behavior (issue4642049)

http://codereview.appspot.com/4642049/diff/6001/src/cmd/goinstall/doc.go
File src/cmd/goinstall/doc.go (right):

http://codereview.appspot.com/4642049/diff/6001/src/cmd/goinstall/doc.go#newcode8
src/cmd/goinstall/doc.go:8: It maintains a list of public Go packages at
http://godashboard.appspot.com/package.
On 2011/06/30 11:50:00, quantumfyre wrote:
> Do we need some extra words to explain that only "public" packages are
reported
> to the dashboard?

Done.

http://codereview.appspot.com/4642049/diff/6001/src/cmd/goinstall/doc.go#newcode76
src/cmd/goinstall/doc.go:76: Search for a Mercurial repository at
"http://example.org/user/foo" or
On 2011/06/30 11:50:00, quantumfyre wrote:
> Should probably put http://example.org/user/foo.hg first, since that's
what the
> code will actually try first.

Done, in that I reversed the order in the code.

http://codereview.appspot.com/4642049/

code review 4667051: cmd/goinstall: try to access via https. (issue4667051)

Reviewers: golang-dev_googlecode.com,

Message:
Hello golang-dev@... (cc: golang-dev@...),

I'd like you to review this change to
http://go.googlecode.com/hg/

Description:
cmd/goinstall: try to access via https.

Please review this at http://codereview.appspot.com/4667051/

Affected files:
   M src/cmd/goinstall/download.go

Index: src/cmd/goinstall/download.go
===================================================================
--- a/src/cmd/goinstall/download.go
+++ b/src/cmd/goinstall/download.go
 <at>  <at>  -77,7 +77,7  <at>  <at> 
  	logLimitFlag:      "-l1",
  	logReleaseFlag:    "-rrelease",
  	check:             "identify",
-	protocols:         []string{"http"},
+	protocols:         []string{"https", "http"},
  	suffix:            ".hg",
  	defaultHosts: []host{
  		 
{regexp.MustCompile(`^([a-z0-9\-]+\.googlecode\.com/hg)(/[a-z0-9A-Z_.\-/]*)?$`), "https", ""},
 <at>  <at>  -98,7 +98,7  <at>  <at> 
  	logLimitFlag:      "",
  	logReleaseFlag:    "release",
  	check:             "peek-remote",
-	protocols:         []string{"git", "http"},
+	protocols:         []string{"git", "https", "http"},
  	suffix:            ".git",
  	defaultHosts: []host{
  		

{regexp.MustCompile(`^(github\.com/[a-z0-9A-Z_.\-]+/[a-z0-9A-Z_.\-]+)(/[a-z0-9A-Z_.\-/]*)?$`),
"http", ".git"},
 <at>  <at>  -117,7 +117,7  <at>  <at> 
  	logLimitFlag:      "-l1",
  	logReleaseFlag:    "release",
  	check:             "info",
-	protocols:         []string{"http", "svn"},
+	protocols:         []string{"https", "http", "svn"},
  	suffix:            ".svn",
  	defaultHosts: []host{
  		 
{regexp.MustCompile(`^([a-z0-9\-]+\.googlecode\.com/svn)(/[a-z0-9A-Z_.\-/]*)?$`), "https", ""},
 <at>  <at>  -138,7 +138,7  <at>  <at> 
  	logLimitFlag:      "-l1",
  	logReleaseFlag:    "-rrelease",
  	check:             "info",
-	protocols:         []string{"http", "bzr"},
+	protocols:         []string{"https", "http", "bzr"},
  	suffix:            ".bzr",
  	defaultHosts: []host{
  		 
{regexp.MustCompile(`^(launchpad\.net/([a-z0-9A-Z_.\-]+(/[a-z0-9A-Z_.\-]+)?| 
~[a-z0-9A-Z_.\-]+/(\+junk| 
[a-z0-9A-Z_.\-]+)/[a-z0-9A-Z_.\-]+))(/[a-z0-9A-Z_.\-/]+)?$`), "https", ""},

Re: code review 4603050: http: warn if the default Content-Type is known to be i... (issue4603050)

*** Abandoned ***

http://codereview.appspot.com/4603050/

code review 4629089: goprotobuf: Fix bug in packed slice decoding. (issue4629089)

Reviewers: adg,

Message:
Hello adg (cc: golang-dev@...),

I'd like you to review this change to
https://goprotobuf.googlecode.com/hg

Description:
goprotobuf: Fix bug in packed slice decoding.

Please review this at http://codereview.appspot.com/4629089/

Affected files:
   M proto/decode.go

Index: proto/decode.go
===================================================================
--- a/proto/decode.go
+++ b/proto/decode.go
 <at>  <at>  -420,17 +420,6  <at>  <at> 
  	sp.Cap = startSize
  }

-// Make *pslice have base address base, length 0, and capacity  
max(startSize, n).
-func initSlicen(pslice unsafe.Pointer, base uintptr, n int) {
-	if n < startSize {
-		n = startSize
-	}
-	sp := (*reflect.SliceHeader)(pslice)
-	sp.Data = base
-	sp.Len = 0
-	sp.Cap = n
-}
-
  // Individual type decoders
  // For each,
  //	u is the decoded value,
 <at>  <at>  -538,10 +527,7  <at>  <at> 

  	y := *x
  	if cap(y) == 0 {
-		// Packed fields are usually only encoded once,
-		// so this branch is almost always executed.
-		// The append in the loop below takes care of other cases.
-		initSlicen(unsafe.Pointer(x), sbase+p.scratch, nb)
+		initSlice(unsafe.Pointer(x), sbase+p.scratch)
  		y = *x
  	}

 <at>  <at>  -587,10 +573,7  <at>  <at> 

  	y := *x
  	if cap(y) == 0 {
-		// Packed fields are usually only encoded once,
-		// so this branch is almost always executed.
-		// The append in the loop below takes care of other cases.
-		initSlicen(unsafe.Pointer(x), sbase+p.scratch, nb)
+		initSlice(unsafe.Pointer(x), sbase+p.scratch)
  		y = *x
  	}

 <at>  <at>  -637,10 +620,7  <at>  <at> 

  	y := *x
  	if cap(y) == 0 {
-		// Packed fields are usually only encoded once,
-		// so this branch is almost always executed.
-		// The append in the loop below takes care of other cases.
-		initSlicen(unsafe.Pointer(x), sbase+p.scratch, nb)
+		initSlice(unsafe.Pointer(x), sbase+p.scratch)
  		y = *x
  	}

Re: code review 4629089: goprotobuf: Fix bug in packed slice decoding. (issue4629089)

LGTM

http://codereview.appspot.com/4629089/

Re: code review 4629089: goprotobuf: Fix bug in packed slice decoding. (issue4629089)

*** Submitted as
http://code.google.com/p/goprotobuf/source/detail?r=97d694cc53c9 ***

goprotobuf: Fix bug in packed slice decoding.

R=adg
CC=golang-dev
http://codereview.appspot.com/4629089

http://codereview.appspot.com/4629089/

code review 4631082: goprotobuf: Revert part of 39eef1b13365. (issue4631082)

Reviewers: adg,

Message:
Hello adg (cc: golang-dev@...),

I'd like you to review this change to
https://goprotobuf.googlecode.com/hg

Description:
goprotobuf: Revert part of 39eef1b13365.

This gets goprotobuf working with release.r58.
After tagging, I'll revert this change.

Please review this at http://codereview.appspot.com/4631082/

Affected files:
   M proto/properties.go

Index: proto/properties.go
===================================================================
--- a/proto/properties.go
+++ b/proto/properties.go
 <at>  <at>  -109,8 +109,8  <at>  <at> 
  	dec     decoder
  	valDec  valueDecoder // set for bool and numeric types only
  	scratch uintptr
-	sizeof  uintptr // calculations of scratch space
-	alignof uintptr
+	sizeof  int // calculations of scratch space
+	alignof int

  	// If this is a packable field, this will be the decoder for the packed  
version of the field.
  	packedDec decoder
 <at>  <at>  -483,7 +483,7  <at>  <at> 
  		}
  		scratch = align(scratch, p.alignof)
  		p.scratch = scratch
-		scratch += p.sizeof
+		scratch += uintptr(p.sizeof)
  		prop.tags[p.Tag] = i
  	}
  	prop.reqCount = reqCount
 <at>  <at>  -496,7 +496,7  <at>  <at> 

  // Alignment of the data in the scratch area.  It doesn't have to be
  // exact, just conservative.  Returns the first number >= o that divides s.
-func align(o uintptr, s uintptr) uintptr {
+func align(o uintptr, s int) uintptr {
  	if s != 0 {
  		for o%uintptr(s) != 0 {
  			o++