aio: Remove obsolete IO worker ID references.

macdice · macdice · commit b4c19da93a08 · 2025-07-12T14:45:36.000+12:00
In an ancient ancestor of this code, the postmaster assigned IDs to IO workers. Now it tracks them in an unordered array and doesn't know their IDs, so it might be confusing to readers that it still referred to their indexes as IDs. No change in behavior, just variable name and error message cleanup. Back-patch to 18. Discussion: https://postgr.es/m/CA%2BhUKG%2BwbaZZ9Nwc_bTopm4f-7vDmCwLk80uKDHj9mq%2BUp0E%2Bg%40mail.gmail.com
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
@@ -4337,15 +4337,15 @@ maybe_start_bgworkers(void)
 static bool
 maybe_reap_io_worker(int pid)
 {
-	for (int id = 0; id < MAX_IO_WORKERS; ++id)
+	for (int i = 0; i < MAX_IO_WORKERS; ++i)
 	{
-		if (io_worker_children[id] &&
-			io_worker_children[id]->pid == pid)
+		if (io_worker_children[i] &&
+			io_worker_children[i]->pid == pid)
 		{
-			ReleasePostmasterChildSlot(io_worker_children[id]);
+			ReleasePostmasterChildSlot(io_worker_children[i]);
 
 			--io_worker_count;
-			io_worker_children[id] = NULL;
+			io_worker_children[i] = NULL;
 			return true;
 		}
 	}
@@ -4389,22 +4389,22 @@ maybe_adjust_io_workers(void)
 	while (io_worker_count < io_workers)
 	{
 		PMChild    *child;
-		int			id;
+		int			i;
 
 		/* find unused entry in io_worker_children array */
-		for (id = 0; id < MAX_IO_WORKERS; ++id)
+		for (i = 0; i < MAX_IO_WORKERS; ++i)
 		{
-			if (io_worker_children[id] == NULL)
+			if (io_worker_children[i] == NULL)
 				break;
 		}
-		if (id == MAX_IO_WORKERS)
-			elog(ERROR, "could not find a free IO worker ID");
+		if (i == MAX_IO_WORKERS)
+			elog(ERROR, "could not find a free IO worker slot");
 
 		/* Try to launch one. */
 		child = StartChildProcess(B_IO_WORKER);
 		if (child != NULL)
 		{
-			io_worker_children[id] = child;
+			io_worker_children[i] = child;
 			++io_worker_count;
 		}
 		else
@@ -4415,11 +4415,11 @@ maybe_adjust_io_workers(void)
 	if (io_worker_count > io_workers)
 	{
 		/* ask the IO worker in the highest slot to exit */
-		for (int id = MAX_IO_WORKERS - 1; id >= 0; --id)
+		for (int i = MAX_IO_WORKERS - 1; i >= 0; --i)
 		{
-			if (io_worker_children[id] != NULL)
+			if (io_worker_children[i] != NULL)
 			{
-				kill(io_worker_children[id]->pid, SIGUSR2);
+				kill(io_worker_children[i]->pid, SIGUSR2);
 				break;
 			}
 		}

Original file line number	Diff line number	Diff line change
`@@ -4337,15 +4337,15 @@ maybe_start_bgworkers(void)`
`4337`	`4337`	`static bool`
`4338`	`4338`	`maybe_reap_io_worker(int pid)`
`4339`	`4339`	`{`
`4340`		`- for (int id = 0; id < MAX_IO_WORKERS; ++id)`
	`4340`	`+ for (int i = 0; i < MAX_IO_WORKERS; ++i)`
`4341`	`4341`	`{`
`4342`		`- if (io_worker_children[id] &&`
`4343`		`- io_worker_children[id]->pid == pid)`
	`4342`	`+ if (io_worker_children[i] &&`
	`4343`	`+ io_worker_children[i]->pid == pid)`
`4344`	`4344`	`{`
`4345`		`- ReleasePostmasterChildSlot(io_worker_children[id]);`
	`4345`	`+ ReleasePostmasterChildSlot(io_worker_children[i]);`
`4346`	`4346`
`4347`	`4347`	`--io_worker_count;`
`4348`		`- io_worker_children[id] = NULL;`
	`4348`	`+ io_worker_children[i] = NULL;`
`4349`	`4349`	`return true;`
`4350`	`4350`	`}`
`4351`	`4351`	`}`
`@@ -4389,22 +4389,22 @@ maybe_adjust_io_workers(void)`
`4389`	`4389`	`while (io_worker_count < io_workers)`
`4390`	`4390`	`{`
`4391`	`4391`	`PMChild *child;`
`4392`		`- int id;`
	`4392`	`+ int i;`
`4393`	`4393`
`4394`	`4394`	`/* find unused entry in io_worker_children array */`
`4395`		`- for (id = 0; id < MAX_IO_WORKERS; ++id)`
	`4395`	`+ for (i = 0; i < MAX_IO_WORKERS; ++i)`
`4396`	`4396`	`{`
`4397`		`- if (io_worker_children[id] == NULL)`
	`4397`	`+ if (io_worker_children[i] == NULL)`
`4398`	`4398`	`break;`
`4399`	`4399`	`}`
`4400`		`- if (id == MAX_IO_WORKERS)`
`4401`		`- elog(ERROR, "could not find a free IO worker ID");`
	`4400`	`+ if (i == MAX_IO_WORKERS)`
	`4401`	`+ elog(ERROR, "could not find a free IO worker slot");`
`4402`	`4402`
`4403`	`4403`	`/* Try to launch one. */`
`4404`	`4404`	`child = StartChildProcess(B_IO_WORKER);`
`4405`	`4405`	`if (child != NULL)`
`4406`	`4406`	`{`
`4407`		`- io_worker_children[id] = child;`
	`4407`	`+ io_worker_children[i] = child;`
`4408`	`4408`	`++io_worker_count;`
`4409`	`4409`	`}`
`4410`	`4410`	`else`
`@@ -4415,11 +4415,11 @@ maybe_adjust_io_workers(void)`
`4415`	`4415`	`if (io_worker_count > io_workers)`
`4416`	`4416`	`{`
`4417`	`4417`	`/* ask the IO worker in the highest slot to exit */`
`4418`		`- for (int id = MAX_IO_WORKERS - 1; id >= 0; --id)`
	`4418`	`+ for (int i = MAX_IO_WORKERS - 1; i >= 0; --i)`
`4419`	`4419`	`{`
`4420`		`- if (io_worker_children[id] != NULL)`
	`4420`	`+ if (io_worker_children[i] != NULL)`
`4421`	`4421`	`{`
`4422`		`- kill(io_worker_children[id]->pid, SIGUSR2);`
	`4422`	`+ kill(io_worker_children[i]->pid, SIGUSR2);`
`4423`	`4423`	`break;`
`4424`	`4424`	`}`
`4425`	`4425`	`}`