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Send the readiness notification when we are ready to accept connections (#8409)

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On a replica we do accept connections, even though commands accessing
the database will operate in read-only mode. But the server is still
already operational and processing commands.

Not sending the readiness notification means that on a HA setup where
the nodes all start as replicas (with replicaof in the config) with
a replica that cannot connect to the master server and which might not
come back in a predictable amount of time or at all, the service
supervisor will end up timing out the service and terminating it, with
no option to promote it to be the main instance. This seems counter to
what the readiness notification is supposed to be signaling.

Instead send the readiness notification when we start accepting
commands, and then send the various server status changes as that.

Fixes: commit 641c64ada10404356fc76c0b56a69b32c76f253c
Fixes: commit dfb598cf3304818e608ceb6b5d9529a293345c4a
This commit is contained in:
Guillem Jover 2021-03-14 07:46:26 +01:00 committed by GitHub
parent 5b48d90049
commit 3a5905fa85
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2 changed files with 4 additions and 6 deletions
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6
src/replication.c
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@ -1873,8 +1873,7 @@ void readSyncBulkPayload(connection *conn) {
serverLog(LL_NOTICE, "MASTER <-> REPLICA sync: Finished with success");
if (server.supervised_mode == SUPERVISED_SYSTEMD) {
redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Finished with success. Ready to accept connections.\n");
redisCommunicateSystemd("READY=1\n");
redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Finished with success. Ready to accept connections in read-write mode.\n");
}
/* Send the initial ACK immediately to put this replica in online state. */
@ -2434,8 +2433,7 @@ void syncWithMaster(connection *conn) {
if (psync_result == PSYNC_CONTINUE) {
serverLog(LL_NOTICE, "MASTER <-> REPLICA sync: Master accepted a Partial Resynchronization.");
if (server.supervised_mode == SUPERVISED_SYSTEMD) {
redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Partial Resynchronization accepted. Ready to accept connections.\n");
redisCommunicateSystemd("READY=1\n");
redisCommunicateSystemd("STATUS=MASTER <-> REPLICA sync: Partial Resynchronization accepted. Ready to accept connections in read-write mode.\n");
}
return;
}

4
src/server.c
View File

@ -6294,10 +6294,10 @@ int main(int argc, char **argv) {
if (server.supervised_mode == SUPERVISED_SYSTEMD) {
if (!server.masterhost) {
redisCommunicateSystemd("STATUS=Ready to accept connections\n");
redisCommunicateSystemd("READY=1\n");
} else {
redisCommunicateSystemd("STATUS=Waiting for MASTER <-> REPLICA sync\n");
redisCommunicateSystemd("STATUS=Ready to accept connections in read-only mode. Waiting for MASTER <-> REPLICA sync\n");
}
redisCommunicateSystemd("READY=1\n");
}
} else {
ACLLoadUsersAtStartup();