| Bug #34338 | Memory leak resulting from procedure cache | ||
|---|---|---|---|
| Submitted: | 6 Feb 2008 2:45 | Modified: | 1 Mar 2008 11:59 |
| Reporter: | Maxim Mass | ||
| Status: | Closed | ||
| Category: | Connector/Net | Severity: | S2 (Serious) |
| Version: | OS: | Any | |
| Assigned to: | Target Version: | ||
[6 Feb 2008 2:48]
Maxim Mass
this is what happens after the cache fills up and the race condition occures
Attachment: mysql.data.dll memory use.GIF (image/gif, text), 40.45 KiB.
[14 Feb 2008 21:23]
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/42308
[14 Feb 2008 21:24]
Reggie Burnett
Verified by visual inspection
[14 Feb 2008 21:24]
Reggie Burnett
Fixed in 5.1.6 and 5.2.1
[14 Feb 2008 21:26]
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/42309
[1 Mar 2008 11:59]
MC Brown
A note has been added to the 5.1.6 and 5.2.1 changelogs: A race condition could occur within the procedure cache resulting the cache contents overflowing beyond the configured cache size.
Description: Adding stored procedure metadata into the ProcedureCache can overfill the maximum number of procedures to cache due to a race condition. Once this the list keeps growing with every unique procedure call and never gets trimmed. How to repeat: Create a catalog with a few thousand stored procedures and call them repeatedly with multiple threads. Eventually the race condition occurs and every call will keep getting inserted. Since the metadata is stored in DataTables the memory fills up quickly. Suggested fix: Changing: if(procHash.Keys.Count == maxSize) to: if(procHash.Keys.Count >= maxSize) would address the issue but locking around this shared hash is probably the more correct way to handle it. Index: C:/MindTouch/redist/MySql Connector 5.14-MT/Source/ProcedureCache.cs =================================================================== --- C:/MindTouch/redist/MySql Connector 5.14-MT/Source/ProcedureCache.cs (revision 7202) +++ C:/MindTouch/redist/MySql Connector 5.14-MT/Source/ProcedureCache.cs (working copy) @@ -52,7 +52,11 @@ { int hash = spName.GetHashCode(); - DataSet ds = (DataSet) procHash[hash]; + DataSet ds = null; + lock (procHash.SyncRoot) { + ds = (DataSet) procHash[hash]; + } + if (ds == null) { ds = AddNew(conn, spName); @@ -80,11 +84,12 @@ DataSet procData = GetProcData(connection, spName); if (maxSize > 0) { - if (procHash.Keys.Count == maxSize) - TrimHash(); int hash = spName.GetHashCode(); lock (procHash.SyncRoot) { + if (procHash.Keys.Count >= maxSize) + TrimHash(); + if (!procHash.ContainsKey(hash)) { procHash[hash] = procData;