MySQL Bugs: #67088: When the general_log is a socket and the reader goes away, mysql quits working.

Bug #67088	When the general_log is a socket and the reader goes away, mysql quits working.
Submitted:	4 Oct 2012 18:47	Modified:	28 Aug 2014 17:34
Reporter:	Rolf Martin-Hoster	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Logging	Severity:	S2 (Serious)
Version:	5.1.54, 5.1.67, 5.5.29, 5.7.0	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
When the general_log is a socket and the reader goes away, mysql quits working.

How to repeat:
Create general_log socket, turn on general log, start consuming socket. Kill consuming application, mysql stops processing queries.

Suggested fix:
Mysql query processing continues to work.

Thank you for the report.

Verified as described.

Repeatable with release server only: debug server crashes like in bug #59847

Noted in 5.5.40, 5.6.21, 5.7.5 changelogs.

If the general query log or slow query log file was set to a FIFO or
socket file, and the file reader went away, the server stopped
executing statements. Now the server detects such files, logs an
error message, and continues with the appropriate log disabled.

revno: 4688
committer: Praveenkumar Hulakund <praveenkumar.hulakund@oracle.com>
branch nick: mysql-5.5
timestamp: Thu 2014-07-17 11:21:18 +0530
message:
  Bug#14757009: WHEN THE GENERAL_LOG IS A SOCKET AND THE READER
                GOES AWAY, MYSQL QUITS WORKING.
  
  Analysis:
  -----------------
  Issue in this bug and in bug 11907705 is, the socket file or
  fifo file is set for general log at command line while starting
  the server. But currently, only regular file can be set for the 
  general log. Instead of reporting any error, the provided files
  are opened for writing and continued. Because of this issues
  mentioned in the bug reports are seen.
  
  As mentioned, only when any non-regular file is set for general
  log at command line while starting the server, these issues are
  seen. If general log file is set to non-regular file from CLI
  using system variable general_log_file then error is reported.
  
  These issues can also be faced with slow query log file, if it is
  set to non-regular file.
  
  Fix:
  -----------------
  Currently while starting the server if we fail to open log file
  then we report an error, disable logging to file and continue.
  To fix issue reported code is modified to check whether file
  is regular file or not before opening it. If file is not a 
  regular file then error is logged to error log and logging to 
  file is disabled.