relay log problem
ken at codeweavers.com
Fri Jan 29 00:50:24 CST 2010
On Jan 28, 2010, at 5:21 PM, Michael Stefaniuc wrote:
> On 01/28/2010 10:59 PM, Henri Verbeet wrote:
>> On 28 January 2010 22:39, Stefan Leichter<Stefan.Leichter at camline.com> wrote:
>>> Is this a know problem? Is a work around available?
>> Yeah, that's a known problem. As a workaround you can use ">>"
>> (append) instead of ">" to redirect to the file. You'll still need the
>> "2>&1" to redirect stderr to stdout, of course.
> That won't workaround the problem. The problem is that there are multiple threads/programs that write at the same time to stdout/stderr.
> I have seen it with fixme/err/warn messages too; even with crash dumps.
Using >> in the shell causes the stdout file descriptor to be opened with O_APPEND. Using 2>&1 makes stderr dup the file descriptor, so it gets the same flag.
With O_APPEND, the kernel ensures that all writes append to the file. Multiple threads or programs using an O_APPEND descriptor can't overwrite each other. If the code uses multiple writes for a single line, then those multiple writes can be interleaved, but can't overwrite. And, for the most part, Wine's debug logging uses single writes so it won't even interleave.
More information about the wine-devel