Shulou(Shulou.com)06/01 Report--

Redis debug command provides several very useful debug functions. This article introduces debug command under redis.

debug segment

Make redis generate segment errors, and if coredump is turned on, a core file will be generated. This command is very simple to implement, write data directly to an illegal address.

*((char*)-1) = 'x';

debug oom

Request a large block of memory, directly let zmalloc trigger oom error

void *ptr = zmalloc(ULONG_MAX); /* Should trigger an out of memory. */

zfree(ptr);

addReply(c,shared.ok);

debug assert

No more explanations.

redisAssertWithInfo(c,c->argv[0],1 == 2);

debug reload

save the current rdb file, and empty the current database, reload rdb, loading is similar to loading at startup, loading process can only serve some read-only requests (such as info, ping, etc.)

rdbSave();

emptyDb();

rdbLoad();

debug loadaof

Empty current database and reload database from aof file

emptyDb();

loadAppendOnlyFile();

debug object

Check the internal information of a key, such as refcount, encoding, serializedlength, etc. The result is as follows

Value at:0x7f21b9479850 refcount:1 encoding:raw serializedlength:6 lru:8462202 lru_seconds_idle:215

debug sdslen

View the current information of an SDS, the current SDS length, and the available memory length. The result is as follows

key_sds_len:3, key_sds_avail:0, val_sds_len:5, val_sds_avail:0

debug populate

Test sharp tools, quickly generate a large number of keys

127.0.0.1:6379> debug populate 10000

OK

127.0.0.1:6379> dbsize

(integer) 10000

debug digest

Generate a summary of the entire database data, which can be used to verify whether the data in two redis databases is consistent.

127.0.0.1:6379> debug digest

7164ae8b6730c8bcade46532e5e4a8015d4cccfb

127.0.0.1:6379> debug digest

7164ae8b6730c8bcade46532e5e4a8015d4cccfb

debug sleep

Test tool, used to simulate a command with a certain time cost, such as debug sleep 0.1 is equivalent to executing a command with a cost of 100 ms.

127.0.0.1:6379> debug sleep 1

OK

(1.00s)

debug error

Test tool, simulate a command execution failure, send debug error, redis will directly return an error response

127.0.0.1:6379> debug error "test"

(error) test

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