From 5a0af47919f5381c4a6e9775dc205d1e96ac5b7e Mon Sep 17 00:00:00 2001 From: Alfranio Correia Date: Fri, 28 Jan 2011 01:25:26 +0000 Subject: BUG#55675 rpl.rpl_log_pos fails sporadically with error binlog truncated in the middle There are two calls to read_log_event() on master in mysql_binlog_send(). Each call reads 19 bytes in this test case and the error of the second read_log_event() is reported to the slave. The second read_log_event() starts from position 94 (75 + 19) to 113 (75 + 19 + 19). Usually, there are two events in the binary log: . 0 - 3 - Header . 4 - 105 - Format Descriptor Event . 106 - 304 - Query Event and both reads fail because operations are reading from invalid positions as expected. However, mysql_binlog_send() does not use the same IO_CACHE that is used to write into binary log (i.e. mysql_bin_log.log_file) for the hot binary log. It opens the binary log file directly by calling open_binlog() and creates a separated IO_CACHE. So there is a possibly that after a master has flushed the binary log file, the content has been cached by the filesystem, and has not updated the disk file. If this happens, then a slave will only see part of the file, and thus the second read_log_event() will report event truncated error. To fix the problem, if the first read_log_event() has failed, we ensure that the second one will try to read from the same position. --- sql/sql_repl.cc | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'sql/sql_repl.cc') diff --git a/sql/sql_repl.cc b/sql/sql_repl.cc index 8c769ce6acf..2a1efab13a9 100644 --- a/sql/sql_repl.cc +++ b/sql/sql_repl.cc @@ -545,8 +545,10 @@ impossible position"; while (!net->error && net->vio != 0 && !thd->killed) { + my_off_t prev_pos= pos; while (!(error = Log_event::read_log_event(&log, packet, log_lock))) { + prev_pos= my_b_tell(&log); #ifndef DBUG_OFF if (max_binlog_dump_events && !left_events--) { @@ -613,8 +615,13 @@ impossible position"; here we were reading binlog that was not closed properly (as a result of a crash ?). treat any corruption as EOF */ - if (binlog_can_be_corrupted && error != LOG_READ_MEM) + if (binlog_can_be_corrupted && + error != LOG_READ_MEM && error != LOG_READ_EOF) + { + my_b_seek(&log, prev_pos); error=LOG_READ_EOF; + } + /* TODO: now that we are logging the offset, check to make sure the recorded offset and the actual match. -- cgit v1.2.1