Github user amyrazz44 commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/1243#discussion_r118668142
--- Diff: src/backend/executor/nodeShareInputScan.c ---
@@ -793,15 +877,72 @@ shareinput_reader_waitready(int share_id,
PlanGenerator planGen)
}
else if(n==0)
{
- elog(DEBUG1, "SISC READER (shareid=%d, slice=%d): Wait
ready time out once",
- share_id, currentSliceId);
+ file_exists = access(writer_lock_file, F_OK);
+ if(file_exists != 0)
+ {
+ elog(DEBUG3, "Wait lock file for writer time
out interval is %d", timeout_interval);
+ if(timeout_interval >=
share_input_scan_wait_lockfile_timeout || flag == true) //If lock file never
exists or disappeared, reader will no longer waiting for writer
+ {
+ elog(LOG, "SISC READER (shareid=%d,
slice=%d): Wait ready time out and break",
+ share_id, currentSliceId);
+ pfree(writer_lock_file);
+ break;
+ }
+ timeout_interval += tval.tv_sec;
+ }
+ else
+ {
+ elog(LOG, "writer lock file of
shareinput_reader_waitready() is %s", writer_lock_file);
+ flag = true;
+ fd_lock = open(writer_lock_file, O_RDONLY);
+ if(fd_lock < 0)
+ {
+ elog(DEBUG3, "Open writer's lock file
%s failed!, error number is %d", writer_lock_file, errno);
--- End diff --
Reader try to lock the lock file which writer created until locked the lock
file successfully which means that writer process quits.
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