# Bugs Fixed
* InnoDB Storage Engine: Issuing INSERT...ON DUPLICATE KEY statements for InnoDB tables from concurrent threads could cause a deadlock, particularly with the INSERT...ON DUPLICATE KEY UPDATE form. The fix avoids deadlocks caused by the same row being accessed by more than one transaction. Deadlocks could still occur when multiple rows are inserted and updated simultaneously by different transactions in inconsistent order; those types of deadlocks require the standard error handling on the application side, of re-trying the transaction.
* An incorrect InnoDB assertion could cause the server to halt. This issue only affected debug builds. The assertion referenced the source file btr0pcur.ic and the variable cursor->pos_state.
* The handle_segfault() signal-handler code in mysqld could itself crash due to calling unsafe functions.
* ARCHIVE tables with NULL columns could cause server crashes or become corrupt under concurrent load.
* Enabling myisam_use_mmap could cause the server to crash.
* Concurrent access to ARCHIVE tables could cause corruption.