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Binlog-in-engine: Fix busy-wait in binlog reader

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A couple of bugs in the checks in ha_innodb_binlog_reader::wait_available()
for if new data is available. These could cause the reader (eg. binlog dump
thread on the master) to busy-loop instead of proper pthread_cond_wait()'ing
on new data to become durable and available for sending to slave.

Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>
This commit is contained in:
Kristian Nielsen 2025-09-30 16:24:03 +02:00
commit cf126c83d4
1 changed files with 14 additions and 4 deletions
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18
storage/innobase/handler/innodb_binlog.cc
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@ -3050,7 +3050,7 @@ ha_innodb_binlog_reader::wait_available(THD *thd,
const struct timespec *abstime)
{
bool is_timeout= false;
bool pending_sync_lsn= 0;
lsn_t pending_sync_lsn= 0;
bool did_enter_cond= false;
PSI_stage_info old_stage;
@ -3077,10 +3077,20 @@ ha_innodb_binlog_reader::wait_available(THD *thd,
As we are holding binlog_durable_mutex, active_binlog_file_no cannot
move during this check.
*/
uint64_t active= active_binlog_file_no.load(std::memory_order_relaxed);
uint64_t cur= active_binlog_file_no.load(std::memory_order_relaxed);
uint64_t durable_offset=
binlog_cur_durable_offset[active & 3].load(std::memory_order_relaxed);
if (chunk_rd.is_before_pos(active, durable_offset))
binlog_cur_durable_offset[cur & 3].load(std::memory_order_relaxed);
if (durable_offset == 0 && chunk_rd.s.file_no + 1 == cur)
{
/*
If active has durable position=0, it means the current durable
position is somewhere in active-1.
*/
cur= chunk_rd.s.file_no;
durable_offset=
binlog_cur_durable_offset[cur & 3].load(std::memory_order_relaxed);
}
if (chunk_rd.is_before_pos(cur, durable_offset))
break;
if (pending_sync_lsn != 0 && ibb_pending_lsn_fifo.flushing_lsn == 0)