We have released ZODB 3.1.2b2 available from the usual place: http://www.zope.org/Products/ZODB3.1 This release includes several critical bug fixes for ZEO. The bugs are more likely to affect sites that see a lot of read conflicts (resolved or unresolved). The bugs can cause data loss or corruption. I would strongly advise ZEO users to consider upgrading. This release has seen more internal stress testing that normal and should be fairly stable for production use. I hope to get a final release out as soon as possible. The release notes (below) describe the fixes in more detail. Jeremy What's new in ZODB3 3.1.2 beta 2? ================================= Fixed critical race conditions in ZEO's cache consistency code that could cause invalidations to be lost or stale data to be written to the cache. These bugs can lead to data loss or data corruption. These bugs are relatively unlikely to be provoked in sites with few conflicts, but the possibility of failure existed any time an object was loaded and stored concurrently. Fixed a bug in conflict resolution that failed to ghostify an object if it was involved in a conflict. (This code may be redundant, but it has been fixed regardless.) The ZEO server was fixed so that it does not perform any I/O until all of a transactions' invalidations are queued. If it performs I/O in the middle of sending invalidations, it would be possible to overlap a load from a client with the invalidation being sent to it. The ZEO cache now handles invalidations atomically. This is the same sort of bug that is described in the 3.1.2b1 section below, but it affects the ZEO cache. Fixed several serious bugs in fsrecover that caused it to fail catastrophically in certain cases because it thought it had found a checkpoint (status "c") record when it was in the middle of the file.