This session will provide a short introduction to the Firebird lock manager and its usage patterns. It will describe how the lock manager can affect the performance of highly loaded systems and outlines the possible bottlenecks and other problems like unexpected lock-ups/freezes that may require special analysis. The structure of the lock table will also be explained. It will also include a detailed description of the fb_lock_print utility and its usage that will enable the research of issues that are related to the lock manager. A few practical examples illustrating how to analyze the utility output will be provided. This session is mainly of interest to Classic Server users and DBAs.

1. Understanding the lock manager with the fb_lock_print utility Dmitry Yemanov mailto:dimitr@firebirdsql.org Firebird Project http://www.firebirdsql.org/

4. Blocking notifications

5. Deadlock detection

6. Monitoring abilities

8. Existence locks (table, procedure, index, collation)

9. Table access locks

10. Transaction locks

14. Small lock table

16. Large lock table

17. LM operations may require IPC

18. Lock Manager in Classic IPC IPC IPC Connection 1 Connection 2 fb_inet_server fb_inet_server fb_lock_mgr Lock table (shmem)

20. Lock owners

21. Lock resources

23. Remappings

24. Hash table of lock keys

25. Inside the Lock Table Lock resource Series: page lock Key: 01:75 State: PR Lock request 1 PR (granted) Lock request 3 EX (pending) Lock request 4 EX (pending) Owner 1 PID = 1008 Owner 3 PID = 870 Owner 4 PID = 114 Lock request 2 PR (granted) Owner 2 PID = 788

28. Blocking = 0x1

29. Blocking seen = 0x100

31. LockSemCount (32) – deprecated in v2.5

34. -l [ocks]

35. -r [equests]

36. -s [eries] <number>

37. -a [ll]

40. Acquires, operations, types, waits

42. -d <database> or -f <lock file>

43. -m

44. Questions?