Re: Thread and process dentifiers (CPU affinity, kill)

[Nix <nix@esperi.org.uk>]

On 20 May 2005, Lennart Sorensen prattled cheerily:
> Maybe Debian compiled their glibc to not do NPTL on i386 yet.  Not sure.

This is not the case. Proof from ps -FT output:

mysql     8473  8473  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8475  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8476  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8477  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8478  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8479  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8480  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8481  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld
mysql     8473  8482  8472  0 29110 14056  0 May22 pts/1  /usr/sbin/mysqld

> Hmm, after checking, it turns out if you use errno in your program, it
> drops to linuxthreads, while using #include <errno.h> makes it able to
> use NPTL when using 2.6 kernel.

This is a distribution-specific patch. glibc as shipped by the FSF simply
refuses to run programs that reference the errno symbol: errno is no
longer an exported symbol at all. (This is reasonable, as such programs
would fail to work on a multithreaded NPTL program in any case.)

The only valid way to gain access to the errno symbol is to
#include <errno.h>. This has been true for as long as glibc2 has existed.

-- 
`Once again, I must remark on the far-reaching extent of my
 ladylike nature.' --- Rosie Taylor
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