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Subjectbug with pipes with newest kernels (2.2.2)?
Hi all, I have some strange problem with pipes with the last kernels
(I really could not trace back when it all began). With 2.2.2 I
noticed that sometime a local mail would delay some minute in
delivering. Now I could verify that asking for a big compressed file
with info (jed -info) will lead to a (ps -lw):

0 1153 524 523 19 0 1092 388 pipe_write S p2 0:00 zcat
-f /usr/info/egcs.info.gz

process that is practically stuck. Sendmail too when it is so slow is
waiting in pipe_write or pipe_read. I am sure it is not a problem with
the file because a zcat -f /usr/info/egcs.info.gz | cat > /dev/null is
almost immediate. 523 is the ppid, jed in this case, reading from the
pipe.

pern:% strace -p 524
write(1, "it the argument count word. Thi"..., 28680

pern:~% ls -l /proc/524/fd
total 0
lrwx------ 1 romano romano 64 Feb 23 16:06 0 -> /dev/ttyp2
l-wx------ 1 romano romano 64 Feb 23 16:06 1 -> pipe:[762]
lrwx------ 1 romano romano 64 Feb 23 16:06 2 -> /dev/tty
lrwx------ 1 romano romano 64 Feb 23 16:06 3 -> /dev/tty
lr-x------ 1 romano romano 64 Feb 23 16:06 4 ->
/usr/info/egcs.info.gz

The calling process:

pern:~% strace -p 523
read(4, 0x80a72f8, 0) = -1 EAGAIN (Resource
temporarily unavailable)
nanosleep(0xbffff67c, 0xbffff67c, 0x401146cc, 0x80972f8, 0x4) = 0
read(4, 0x80a72f8, 0) = -1 EAGAIN (Resource
temporarily unavailable)
nanosleep(0xbffff67c, 0xbffff67c, 0x401146cc, 0x80972f8, 0x4) = 0
read(4, 0x80a72f8, 0) = -1 EAGAIN (Resource
temporarily unavailable)
... and repeating

ls -l /proc/523/fd
total 0
lrwx------ 1 romano romano 64 Feb 23 16:09 0 -> /dev/ttyp2
lrwx------ 1 romano romano 64 Feb 23 16:09 1 -> /dev/ttyp2
lrwx------ 1 romano romano 64 Feb 23 16:09 2 -> /dev/tty
lrwx------ 1 romano romano 64 Feb 23 16:09 3 -> /dev/tty
lr-x------ 1 romano romano 64 Feb 23 16:09 4 -> pipe:[762]

Linux pern 2.2.2 #5 Tue Feb 23 10:45:28 CET 1999 i686 unknown

pern:~% ls -l /usr/info/egcs.info.gz
-rw-r--r-- 1 root root 368592 Oct 14 13:23 /usr/info/egcs.info.gz

sendmail ends with a timeout and recovering. Jed is still waiting (5
minutes and counting). I am sure that in the past it worked.

Any idea on what's happening here?

Romano

--
Romano Giannetti, Professor - Univ. Pontificia Comillas (Madrid, Spain)
Electronic Engineer - phone +34 915 422 800 ext 2410 fax +34 915 596 569

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