Setnx command execution failed due to full redis memory

One 、 Problem occurs

Under normal circumstances , adopt setnx Set a lock , It should be 1s After expired （ Prevent concurrent requests , Handle the same logic ）, But what actually happened was , Deal with the following logic for the first time , Throw an exception . explain setnx Function returned false.

$redis_key_lock = 'lock'; 

//@todo  Set up a 1s Lock of 
$lock           = $redis->setnx($redis_key_lock, 1);

//@todo  Will be locked in 1s After expired 
$redis->expire($redis_key_lock, 1);

if ($lock) {
    //  Perform other logic 
} else {
    throw new \Exception(" Lock present ");
}

Two 、 Troubleshoot problems

redis Your memory is full

adopt redis.conf Check it out. redis Expiration strategy

# maxmemory-policy volatile-lru

explain redis The default expiration policy is used noeviction

Default expiration policy  noeviction Not for expired keys Do any cleaning , When the memory is full , Will refuse to perform all write operations , By flipping through redis The configuration file , You can find relevant tips , And in addition to setnx, Other write operation related instructions , Will fail .

  The solution is to quickly release redis Memory , Give Way setnx The command can be executed normally .