Path: utzoo!utgpu!news-server.csri.toronto.edu!qucis!jorgnsn From: jorgnsn@qucis.queensu.ca (John Jorgensen) Newsgroups: comp.lang.postscript Subject: Is HP PostScript known to hang mysteriously? Message-ID: <1019@quiddity.queensu.CA> Date: 4 Dec 90 20:50:46 GMT Sender: jorgnsn@qucis.queensu.CA Distribution: world Organization: Queen's University, Kingston Lines: 97 We have been experiencing a maddeningly intermittent problem with two HP LaserJet IIIs with HP's PostScript cartridge. In brief, the printers occasionally hang indefinitely while printing jobs, and have to be reset or power-cycled before they will start printing again. The problem does not seem to be bugs in the submitted PostScript programs, because the exact same files will print perfectly after the printer is reset. I am posting in the hope that someone else might have seen similar problems, and either solved them, or been able to link them to known bugs in HP's PostScript. Here are the long, gory details: We have two LaserJet IIIs with HP's PostScript cartridge, hanging off the MTI-1600 board of a Sun 3/160. Occasionally the printers hang (from 0 to 4 times a week, where each printer sees 250-450 print jobs per week, totaling 1000-3000 pages). "PROCESSING DATA" shows up in the message window, and stays there for tens of minutes. Because I have been able to print the identical jobs after resetting the printer, I know that the problem is not just that the PostScript program is doing a great deal of computation. Sometimes I have been able to take the printer offline, reset it from the front panel, and had it work fine afterwards. More often, when I try to take the printer offline, the message "OFFLINE PENDING" appears on the screen, but the printer never goes offline. In those cases, I have had to turn the printer off and on to bring it back to the real world. Generally speaking, resubmitting the same job after resetting or power-cycling the printer results in perfect output and no hitches. The times that I have seen the printer hang again on the same job, it was on a different page. There doesn't seem to be anything special about the pages where the printer hangs (no fancy bitmaps or complicated graphics, for example). Most of the output that causes the problem has been produced by dvitps, the DVI-to-PostScript translator that we use, but the printers have also hung on output from tpscript, a public domain DITROFF-to-PostScript translator. Neither of these programs has produced similar problems on our old Apple LaserWriter I (but I suppose they could be tickling some subtle incompatibility between HP's PostScript and Apple's). I have some evidence that the difficulty is not a communications problem between the Sun and the printers: First, the spooler logs have frequently shown that as far as the host was concerned, the entire job was sent, even though there were still several pages to print after the point where the printer hung--so it seems that the printer was able to continue receiving and buffering characters despite not being able to output anything. Second, in cases where the host had not sent the entire file, I have used Sun's pstat command to look at the STREAMS data structures for the printer's serial line and confirmed that the host was blocked on that line with a full buffer. Third--and this is the weird one--I have enabled debugging output in the PostScript that dvitps produces and the resulting messages indicate not only that the PostScript program has started work on the page after the last page it managed to print, but that sometimes that it is _two_ pages ahead of the last page to print. That last point, combined with the whirring noise that sometimes accompanies the hanging, makes me wonder if the problem is at least sometimes associated with the printer's attempt to output a page. There are, however, no paper jams associated with this problem. I have modified our spooler to bracket each print job with a "vmstatus" command, to check for memory leaks. There don't seem to be any. Are there other status commands I could insert to indicate if some evil condition is gradually building up between jobs? Now for the treatments I have either tried or considered. When the problems first surfaced, shortly after we installed the printers, I moved the PostScript cartridges from the right to the left slot, and imagined the problem went away for a while (more likely users just stopped bothering to tell me about it). I have considered replacing dvitps and tpscript with alternative programs (probably Tomas Rokiki's dvips and GNU's groff), but am reluctant to dragoon our users into this until I have some clearer indication that it will do some good. I have also thought of moving the printer's serial lines from the Sun's MTI boards to the ports on the CPU board, but again am reluctant to shift equipment around without knowing more about what I am doing. With the problem so intermittent, even deciding whether it has gone away is difficult. So has anybody out there seen similar problems? Are there known problems with HP's PostScript? Has anybody actually managed to read this far? Email me, and I will post a summary. Thanks for your help, John Jorgensen jorgnsn@qucis.queensu.ca (613) 545 6784 Systems Programmer, Dept. of Computing Science, Queen's University Brought to you by Super Global Mega Corp .com