| Summary: | Deadlock in FileHandler.java when log is rotated | ||
|---|---|---|---|
| Product: | Tomcat 7 | Reporter: | Alex Chachanashvili <achacha> |
| Component: | Catalina | Assignee: | Tomcat Developers Mailing List <dev> |
| Status: | RESOLVED FIXED | ||
| Severity: | major | ||
| Priority: | P2 | ||
| Version: | 7.0.62 | ||
| Target Milestone: | --- | ||
| Hardware: | PC | ||
| OS: | Linux | ||
Thanks for the report. The fix is provided for Tomcat 7 trunk and will be available with 7.0.63 onwards. Regards, Violeta |
Tomcat 7 will deadlock when a log file is rotated. This issue has been fixed in latest tomcat 6 and tomcat 8 but not in tomcat 7. The issue is in following code (apache-tomcat-7.0.62-src/java/org/apache/juli/FileHandler.java:188) } finally { writerLock.writeLock().unlock(); // Down grade to read-lock. This ensures the writer remains valid // until the log message is written writerLock.readLock().lock(); } } Despite the comment the order is wrong, you have to acquire a read lock then release write lock to make sure the race condition does not occur. The correct way to do it is: } finally { writerLock.readLock().lock(); writerLock.writeLock().unlock(); } } In tomcat 6 (apache-tomcat-6.0.44-src/java/org/apache/juli/FileHandler.java:187) and tomcat 8 (apache-tomcat-8.0.22-src/java/org/apache/juli/FileHandler.java:186) the order is correct.