#20033 [Fbk->Opn]: Echoing/fputsing ~11k+ of data to STDOUT causes problem

ID: 20033 User updated by: ces@vaultbbs.com Reported By: ces@vaultbbs.com -Status: Feedback +Status: Open Bug Type: Sockets related Operating System: Red Hat 7.3 PHP Version: 4CVS-2002-10-22 New Comment: I added requested fflush on $logfile after each fputs. It still indicates that it is dying on the "echo". I.e., logfile shows "Echoing line" but never reports "Sent." Additional important correction: I'm not sure whether behavior has changed or if I was just wrong before, but when the problem presents itself the script IS shutting down and the TCP/IP connection IS disconnected. In fact, it does so cleanly. It executes my registered shutdown function. In that function I had it write to the logfile and it shows that after the last "Echoing" line it DOES go through the shutdown function. Connection_status() within the shutdown function reports "1" (aborted), but the client side definitely didn't request the abort. I have also refined the loop so that the possible infinite loop situation is handled. This is a welcome improvement to my code to handle an "impossible" situation (impossible because it is constrained elsewhere by logic) but it didn't have any effect on the current problem. Previous Comments: ------------------------------------------------------------------------ [2002-10-23 06:26:33] msopacua@php.net while(ftell($mailfile) < $EndOfMessagePos) This line has the potential to cause a indefinete loop and there's no escape code in the loop, which breaks it. ftell will return FALSE if an error occurs, which in numerical comparison resolves to 0. Can you change that to: while(ftell($mailfile) and ftell($mailfile) < $EndOfMessagePos) ------------------------------------------------------------------------ [2002-10-23 03:54:00] wez@php.net It's more likely to be a problem with fgets; could you try fflush($logfile) ing after the fputs lines, just to make sure that they're not waiting in the buffer. Also, when php hangs, is it using a lot of CPU? ------------------------------------------------------------------------ [2002-10-22 17:42:38] ces@vaultbbs.com Code I am using is: while(ftell($mailfile) < $EndOfMessagePos) { fputs($logfile, "Getting line\n"); $line = fgets($mailfile, 4096); fputs($logfile, "Echoing line\n"); echo "$line\r\n"; $fst += strlen($line); fputs($logfile, "Sent $fst: $line\n"); } echo ".\r\n"; fputs($logfile, "Sent: CRLF\n"); fclose($logfile); End of log file returns: --START-- Getting line Echoing line Sent 11060: (unimportant email content) Getting line Echoing line Sent 11147: (unimportant email content) Getting line Echoing line --END-- Thus it appears to be hanging on the "echo" line. Again, this problem only presents itself when the script is running as a full server on a "clean" connection. If the same exact test is run connecting via the telnet command to port 110 or by running the script from the command-line there is no problem. It is my guess that the telnet command introduces some kind of flow control that is not present when I open a "real" POP3 connection to the same port. ------------------------------------------------------------------------ [2002-10-22 16:57:05] wez@php.net Can you isolate the line of code that causes the hang? Use printf to output a note before each function you suspect of causing the problem; the last line output by the script will tell you which one has hung. We need to narrow it down to either sockets (as in ext/socket), or streams (fgets, fread, fwrite etc.), or output buffer -- three unrelated areas. ------------------------------------------------------------------------ [2002-10-22 16:34:52] ces@vaultbbs.com Additional info: If I switch my binary back to php 4.1.3, my POP3 server script works 100% inasmuch as this bug is concerned. Additionally, I can confirm that something is crashing in PHP in that if I dump data to a log file, the logfile ends where the data turns to garbage. An additional log entry should be made when the message dump is complete. This is never executed. This is a weird problem that seems to cause PHP to hang, not core dump, and not terminate the TCP/IP connection but causes PHP to just dump garbage and just hang. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/20033 -- Edit this bug report at http://bugs.php.net/?id=20033&edit=1