by sheadl » Sun, 16 Feb 2003 00:12:58
by Chuck Dillo » Sun, 16 Feb 2003 01:22:30
-- ced
--
Chuck Dillon
Senior Software Engineer
NimbleGen Systems Inc.
by Fletcher Glen » Thu, 20 Feb 2003 02:02:30
> Hello All,
> I have a problem I hope someone here can answer. I have multiple
> sockets that I am watching with select. I get an indication from
> select that there is data to be read from a socket I am interested in.
> When I go to retrieve that data, read returns 0 bytes. When is it
> possible that select can return that there is data available from a
> particular socket but read dosen't have data available for that
> socket? My OS is AIX.
--
Fletcher Glenn
1. When do read() return 0 despite that select() returned 1
I have a somewhat unstable program that causes strange crashes.
The code is multi-threaded using sproc(). Sometimes one of the
threads starts to loop calling a select() with a filedescriptor
of a readble pipe, gets an indication of readability, does a
read() call wich returns 0, and so on.
do {
noOfRead = select(...);
if (noOfRead==1) {
howMany = read(...);
if (howMany > 0) {
// Do something useful
} else if (howMany==-1) {
// Error output
abort();
}
}
I am not asking about why the program crashes. I am just
curious why select() indicates bytes to be read, but read()
indicates no bytes and returns 0. If I can solve that, this
part of the code can do a graceful exit. As it is today,
this part of the codes get a lot of interest from people
trying to locate the cause of error, since it loops.
I would like a way to stop looping and produce a correct
diagnostic message. Today I get contradicting messages:
select says "go ahead and read" and read() says "nothing to read".
2. 2.4.19-rc1 sending SIGALRM to exec'd process
3. Select() returning 0 even though data on socket
4. Configuring X on Acernote light.
5. 2.5.62: /proc/ide/via reads return incomplete data, Bug #374
7. dos emulator & security key
8. Socket problem: select() not returning when a new connection is available
9. (?) CGI script not always returning data
10. unamex Returns Binary Form of uname Data?
11. 2.5.62: /proc/ide/aec62xx returns incomplete data [1/17]
12. 2.5.62: /proc/ide/amd74xx returns incomplete data [3/17]