| Bug #22301 | ndb: File_class::size() is not thread safe | ||
|---|---|---|---|
| Submitted: | 13 Sep 2006 11:38 | Modified: | 3 Jan 2007 3:34 |
| Reporter: | Stewart Smith | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Cluster: Cluster (NDB) storage engine | Severity: | S3 (Non-critical) |
| Version: | 5.0,5.1 | OS: | |
| Assigned to: | Stewart Smith | CPU Architecture: | Any |
[13 Sep 2006 12:09]
Stewart Smith
on closer examination, the likelyhood of hitting this is *very* rare due to most log messages being surrounded by other mutexes (node id mutex, config mutex) that it's not surprising nobody has ever noticed this before.
[27 Oct 2006 8:59]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/14459 ChangeSet@1.2276, 2006-10-27 18:59:20+10:00, stewart@willster.(none) +3 -0 BUG#22301 ndb: File_class::size() is not thread safe
[8 Nov 2006 4:21]
Stewart Smith
pushed to 5.1-ndb
[4 Dec 2006 8:31]
Martin Skold
Pushed to 5.1.14
[29 Dec 2006 0:36]
Stewart Smith
pushed to 5.0-ndb
[29 Dec 2006 8:19]
Stewart Smith
pushed to 5.0.34
[3 Jan 2007 3:34]
Jon Stephens
No changes visible to end users; closed w/o further action at this time.
Description: 00037 File_class::size(FILE* f) 00038 { 00039 long cur_pos = 0, length = 0; 00040 00041 cur_pos = ::ftell(f); 00042 ::fseek(f, 0, SEEK_END); 00043 length = ::ftell(f); 00044 ::fseek(f, cur_pos, SEEK_SET); // restore original position 00045 00046 return length; 00047 } the following could happen: thread A: ftell thread B: write log message thread A: seek(END) thread A: ftell thread A: fseek back to before the log message was written, overwriting the log message. How to repeat: be very, very unlucky. can be seen with helgrind. ==21063== by 0x80F2304: File_class::size(_IO_FILE*) (File.cpp:41) ==21063== by 0x80F27E6: File_class::size() const (File.cpp:163) ==21063== by 0x80EFBEE: FileLogHandler::isTimeForNewFile() (FileLogHandler.cpp:141) ==21063== by 0x80EFDCE: FileLogHandler::writeFooter() (FileLogHandler.cpp:116) ==21063== by 0x80EF0AF: LogHandler::append_impl(char const*, Logger::LoggerLevel, char const*) (LogHandler.cpp:90) ==21063== by 0x80EF1FB: LogHandler::append(char const*, Logger::LoggerLevel, char const*) (LogHandler.cpp:72) ==21063== by 0x80EE041: Logger::log(Logger::LoggerLevel, char const*, char*) const (Logger.cpp:369) ==21063== by 0x80EE0E0: Logger::info(char const*, ...) const (Logger.cpp:342) ==21063== by 0x808F777: MgmtSrvr::Allocated_resources::~Allocated_resources() (MgmtSrvr.cpp:2520) ==21063== by 0x8097582: MgmApiSession::~MgmApiSession() (Services.cpp:307) Suggested fix: use stat(2) instead.