PPD: Message Processing Bottlenecks

[michaelrsweet]

Version: 1.6-current
CUPS.org User: chulbert

The currently recommended approach for encoding binary data in PPD files through PPD: messages from a filter suffers serious performance issues when the amount of data becomes large. Even more so when the PPD file is large.

Each PPD: message causes the PPD file to be read by line and written to a copy. If a filter emits 10s or 100s of messages this can result in 10s or 100s of megabytes of disk access, which can make the scheduler non-responsive. On OS X, this can lock the application and deny service to concurrent users.

While concise encoding, compression and multiple attributes per PPD: message help reduce the impact, the problem remains unsolved.

[michaelrsweet]

CUPS.org User: mike

Fixed in Subversion repository.

[michaelrsweet]

"str4075.patch":

Index: scheduler/job.c

--- scheduler/job.c (revision 10492)
+++ scheduler/job.c (working copy)
@@ -3363,6 +3363,21 @@
cupsArrayRemove(PrintingJobs, job);

/*

• * Apply any PPD updates...
• */

• if (job->num_keywords)
• {
• if (cupsdUpdatePrinterPPD(job->printer, job->num_keywords, job->keywords))

•  cupsdSetPrinterAttrs(job->printer);
  
• cupsFreeOptions(job->num_keywords, job->keywords);

• job->num_keywords = 0;
• job->keywords = NULL;
• }

• /*
  • Clear the printer <-> job association...
    */

@@ -4827,18 +4842,10 @@
* Set attribute(s)...
*/

•  int      num_keywords;   /\* Number of keywords */
  

- cups_option_t keywords; / Keywords */

   cupsdLogJob(job, CUPSD_LOG_DEBUG, "PPD: %s", message);

- num_keywords = cupsParseOptions(message, 0, &keywords);

•  if (cupsdUpdatePrinterPPD(job->printer, num_keywords, keywords))
  

- cupsdSetPrinterAttrs(job->printer);

•  cupsFreeOptions(num_keywords, keywords);
  

•  job->num_keywords = cupsParseOptions(message, job->num_keywords,
  

•                                       &job->keywords);
  

  }
  else
  {
  Index: scheduler/job.h

  --- scheduler/job.h (revision 10492)
  +++ scheduler/job.h (working copy)
  @@ -80,6 +80,8 @@
  void profile; / Security profile /
  cups_array_t *history; / Debug log history /
  int progress; / Printing progress */
• int num_keywords; /* Number of PPD keywords */
• cups_option_t keywords; / PPD keywords */
  };

typedef struct cupsd_joblog_s /**** Job log message ****/