diff options
| -rw-r--r-- | contrib/pg_upgrade/parallel.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/contrib/pg_upgrade/parallel.c b/contrib/pg_upgrade/parallel.c index 38ded518329..f00bb7181a7 100644 --- a/contrib/pg_upgrade/parallel.c +++ b/contrib/pg_upgrade/parallel.c @@ -130,7 +130,7 @@ parallel_exec_prog(const char *log_file, const char *opt_log_file, /* fork failed */ pg_log(PG_FATAL, "could not create worker process: %s\n", strerror(errno)); #else - /* use first empty array element */ + /* empty array element are always at the end */ new_arg = exec_thread_args[parallel_jobs - 1]; /* Can only pass one pointer into the function, so use a struct */ @@ -244,7 +244,7 @@ parallel_transfer_all_new_dbs(DbInfoArr *old_db_arr, DbInfoArr *new_db_arr, /* fork failed */ pg_log(PG_FATAL, "could not create worker process: %s\n", strerror(errno)); #else - /* use first empty array element */ + /* empty array element are always at the end */ new_arg = transfer_thread_args[parallel_jobs - 1]; /* Can only pass one pointer into the function, so use a struct */ @@ -339,10 +339,10 @@ reap_child(bool wait_for_child) thread_handles[thread_num] = thread_handles[parallel_jobs - 1]; /* - * We must swap the arg struct pointers because the thread we just - * moved is active, and we must make sure it is not reused by the next - * created thread. Instead, the new thread will use the arg struct of - * the thread that just died. + * Move last active thead arg struct into the now-dead slot, + * and the now-dead slot to the end for reuse by the next thread. + * Though the thread struct is in use by another thread, we can + * safely swap the struct pointers within the array. */ tmp_args = cur_thread_args[thread_num]; cur_thread_args[thread_num] = cur_thread_args[parallel_jobs - 1]; |