runtime/debug: WriteHeapDump does not write a heapdump for go1.3beta2 windows

[gopherbot]

by marcel.lanz:

What does 'go version' print?
go version go1.3beta2 windows/386

What steps reproduce the problem?

http://play.golang.org/p/jcL5Ab1ivY
build and run the programm.

What happened?
It produced a file named heapdump_win32 but of size 0 bytes

What should have happened instead?
it should write a heapdump to a file named heapdump_win32 with file size > 0 bytes

Please provide any additional information below:
Windows is Windows7, 64Bit
runtime/debug.WriteHeapDump works on OSX with: go version go1.3beta2 darwin/amd64

package main

import (
    "fmt"
    "os"
    "runtime/debug"
)

func main() {

    fmt.Println("writing heapdump")
    f, err := os.Create("heapdump_wind32")
    if err != nil {
        panic(err)
    }

    debug.WriteHeapDump(f.Fd())
    f.Close()
}

produces a file of 0 bytes on Windows and 137410 bytes on OSX

[ianlancetaylor]

Comment 1:

Labels changed: added repo-main, release-go1.4.

[ianlancetaylor]

Comment 2:

Labels changed: added os-windows.

[randall77]

Comment 3:

Owner changed to @randall77.

[randall77]

Comment 4:

It looks like our windows write() implementation only handles stdout and stderr file
descriptors.  This is going to be nontrivial to fix.  Any windows experts out there know
how to write to a os.Create().Fd()?  Is it even possible?
os_windows.c:
int32
runtime·write(int32 fd, void *buf, int32 n)
{
    void *handle;
    uint32 written;
    written = 0;
    switch(fd) {
    case 1:
        handle = runtime·stdcall(runtime·GetStdHandle, 1, (uintptr)-11);
        break;
    case 2:
        handle = runtime·stdcall(runtime·GetStdHandle, 1, (uintptr)-12);
        break;
    default:
        return -1;
    }
    runtime·stdcall(runtime·WriteFile, 5, handle, buf, (uintptr)n, &written, (uintptr)0);
    return written;
}

[minux]

Comment 5:

I will fix this one. heapdump is introduced in this cycle, so i think we can
fix it before 1.3.

Labels changed: added release-go1.3maybe, removed release-go1.4.

[gopherbot]

Comment 6:

CL https://golang.org/cl/93640044 mentions this issue.

[minux]

Comment 7:

This issue was closed by revision a68b9be.

Status changed to Fixed.