Stuck on Redis Replication #ZN8

Jbordhen · May 14, 2024, 5:32pm

I am trying this challenge in Golang. As you can see from the log, I am getting the same output from both master and slave. But the test is getting different response.


Debug = true
[replication-11] Running tests for Replication > Stage #11: Single-replica propagation
[replication-11] $ ./spawn_redis_server.sh --port 6379
[your_program] Logs from your program will appear here!
[replication-11] replica: $ redis-cli PING
[replication-11] replica: Sent bytes: "*1\r\n$4\r\nPING\r\n"
[replication-11] replica: Received bytes: "+PONG\r\n"
[replication-11] replica: Received RESP value: "PONG"
[your_program] Accepted connection from [::1]:56026
[your_program] Accepted connection from [::1]:56012
[your_program] master 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb +PONG
[your_program] 
[replication-11] Received "PONG"
[replication-11] replica: $ redis-cli REPLCONF listening-port 6380
[replication-11] replica: Sent bytes: "*3\r\n$8\r\nREPLCONF\r\n$14\r\nlistening-port\r\n$4\r\n6380\r\n"
[your_program] master 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb +OK
[your_program] 
[replication-11] replica: Received bytes: "+OK\r\n"
[replication-11] replica: Received RESP value: "OK"
[replication-11] Received "OK"
[replication-11] replica: $ redis-cli REPLCONF capa psync2
[replication-11] replica: Sent bytes: "*3\r\n$8\r\nREPLCONF\r\n$4\r\ncapa\r\n$6\r\npsync2\r\n"
[your_program] master 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb +OK
[your_program] 
[replication-11] replica: Received bytes: "+OK\r\n"
[replication-11] replica: Received RESP value: "OK"
[replication-11] Received "OK"
[replication-11] replica: $ redis-cli PSYNC ? -1
[replication-11] replica: Sent bytes: "*3\r\n$5\r\nPSYNC\r\n$1\r\n?\r\n$2\r\n-1\r\n"
[your_program] master 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb +FULLRESYNC 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb 0
[your_program] 
[replication-11] replica: Received bytes: "+FULLRESYNC 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb 0\r\n"
[replication-11] replica: Received RESP value: "FULLRESYNC 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb 0"
[replication-11] Received "FULLRESYNC 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb 0"
[replication-11] Reading RDB file...
[your_program] slaveList [0xc00009c040]
[replication-11] replica: Received bytes: "$88\r\nREDIS0011\xfa\tredis-ver\x057.2.0\xfa\nredis-bits\xc0@\xfa\x05ctime\xc2m\b\xbce\xfa\bused-mem°\xc4\x10\x00\xfa\baof-base\xc0\x00\xff\xf0n;\xfe\xc0\xffZ\xa2"
[replication-11] Received RDB file
[replication-11] client: $ redis-cli SET foo 123
[replication-11] client: Sent bytes: "*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\n123\r\n"
[replication-11] client: Received bytes: "+OK\r\n"
[replication-11] client: Received RESP value: "OK"
[your_program] *3
[your_program] $3
[your_program] SET
[your_program] $3
[your_program] foo
[your_program] $3
[your_program] 123
[your_program] 
[your_program] Write to slave 6fc33975-4b18-4d16-ae2f-716f7e67eb3d@ [::1]:56026Command SET: *3
[your_program] $3
[your_program] SET
[your_program] $3
[your_program] foo
[your_program] $3
[your_program] 123
[your_program] master 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb +OK
[your_program] 
[replication-11] Received "OK"
[replication-11] client: $ redis-cli SET bar 456
[replication-11] client: Sent bytes: "*3\r\n$3\r\nSET\r\n$3\r\nbar\r\n$3\r\n456\r\n"
[your_program] *3
[your_program] $3
[your_program] SET
[your_program] $3
[your_program] bar
[your_program] $3
[your_program] 456
[your_program] 
[your_program] Write to slave 6fc33975-4b18-4d16-ae2f-716f7e67eb3d@ [::1]:56026Command SET: *3
[your_program] $3
[your_program] SET
[your_program] $3
[your_program] bar
[your_program] $3
[your_program] 456
[your_program] master 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb +OK
[your_program] 
[replication-11] client: Received bytes: "+OK\r\n"
[replication-11] client: Received RESP value: "OK"
[replication-11] Received "OK"
[replication-11] client: $ redis-cli SET baz 789
[replication-11] client: Sent bytes: "*3\r\n$3\r\nSET\r\n$3\r\nbaz\r\n$3\r\n789\r\n"
[replication-11] client: Received bytes: "+OK\r\n"
[replication-11] client: Received RESP value: "OK"
[your_program] *3
[your_program] $3
[your_program] SET
[your_program] $3
[your_program] baz
[your_program] $3
[your_program] 789
[your_program] 
[your_program] Write to slave 6fc33975-4b18-4d16-ae2f-716f7e67eb3d@ [::1]:56026Command SET: *3
[your_program] $3
[your_program] SET
[your_program] $3
[your_program] baz
[your_program] $3
[replication-11] Received "OK"
[replication-11] Sent 3 SET commands to master successfully.
[replication-11] replica: Expecting "SET foo 123" to be propagated
[replication-11] replica: Received bytes: "*3\r\n$3\r\nSET\r\n$3\r\nfoo\r\n$3\r\n123\r\n"
[replication-11] replica: Received RESP value: ["SET", "foo", "123"]
[replication-11] Received ["SET", "foo", "123"]
[replication-11] replica: Expecting "SET bar 456" to be propagated
[your_program] 789
[replication-11] Received: "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
[replication-11]            ^ error
[replication-11] Error: "\x00" is not a valid start of a RESP2 value (expected +, -, :, $ or *)
[replication-11] Test failed
[replication-11] Terminating program
[your_program] master 8371b4fb1155b71f4a04d3e1bc3e18c4a990aeeb +OK
[your_program] 
[your_program] Error reading from connection:  read tcp [::1]:6379->[::1]:56026: read: connection reset by peer
[your_program] Error reading from connection:  EOF
[replication-11] Program terminated successfully`Preformatted text`

Thank you .

Jbordhen · May 17, 2024, 2:52pm

So, I had to replace the args with “\x00” and the test passed.

Any idea why I have to remove “\x00” this when it’s the exact same string?

Correct version

				for _, slave := range server.SlaveList {
					input := strings.Replace(input, "\x00", "", -1)
					_, err := slave.conn.Write([]byte(input))

					// fmt.Printf("Write to slave %s@ %s", slave.id, slave.conn.RemoteAddr())

					if err != nil {
						fmt.Println("Error write to slave: ", err.Error())
						fmt.Println(slave.conn)
						slave.conn.Close()
						continue
					}
				}

Old version

				for _, slave := range server.SlaveList {
					_, err := slave.conn.Write([]byte(input))

					// fmt.Printf("Write to slave %s@ %s", slave.id, slave.conn.RemoteAddr())

					if err != nil {
						fmt.Println("Error write to slave: ", err.Error())
						fmt.Println(slave.conn)
						slave.conn.Close()
						continue
					}
				}

rohitpaulk · May 27, 2024, 9:43pm

@Jbordhen this can happen if you’re initializing a fixed size byte array (something like var arr [1024]byte) but only reading a smaller amount of bytes into it. The rest of the bytes will be null bytes (\x00) by default.

Hard to tell if it’s exactly this without seeing how input is constructed, but this is the most likely cause

rohitpaulk · June 3, 2024, 7:12pm

Marking as closed for now, please let us know if you still need help!

system · June 4, 2024, 1:54am

Note: I’ve updated the title of this post to include the stage ID (#ZN8). You can learn about the stages rename here: Upcoming change: Stages overhaul.

system · June 9, 2024, 1:55am

This topic was automatically closed 5 days after the last reply. New replies are no longer allowed.

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Stuck on Redis Replication #ZN8

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