Jedis/Redis SocketTimeout exception on Lua scripts - lua

Question

We are using lua scripts to perform batch deletes of data on updates to our DB. Jedis executes the lua script using a pipeline.
local result = redis.call('lrange',key,0,12470)
for i,k in ipairs(result) do
redis.call('del',k)
redis.call('ltrim',key,1,k)
end
try (Jedis jedis = jedisPool.getResource()) {
Pipeline pipeline = jedis.pipelined();
long len = jedis.llen(table);
String script = String.format(DELETE_LUA_SCRIPT, table, len);
LOGGER.info(script);
pipeline.eval(script);
pipeline.sync();
} catch (JedisConnectionException e) {
LOGGER.info(e.getMessage());
}
For large ranges we notice that the lua scripts slow down and we get SocketTimeOutExceptions.
running redis-cli slowlog displays only the lua scripts that have taken too long to execute.
Is there a better way to do this? is my lua script blocking?
When I use just pipeline to do the batch deletes, the slowlog also returns slow queries.
try (Jedis jedis = jedisPool.getResource()) {
Pipeline pipeline = jedis.pipelined();
long len = jedis.llen(table);
List<String> queriesContainingTable = jedis.lrange(table,0,len);
if(queriesContainingTable.size() > 0) {
for (String query: queriesContainingTable) {
pipeline.del(query);
pipeline.lrem(table,1,query);
}
pipeline.sync();
}
} catch (JedisConnectionException e) {
LOGGER.info("CACHE INVALIDATE FAIL:"+e.getMessage());
}

Answer 1

slowlog is capable of storing top 128 slowlogs alone (can be changed in redis.conf slowlog-max-len 128). So your 1st model of using LUA script is surely a blocking one.
If you delete such a number (12470) one by one it is surely a blocking one as it take more time to complete. Out of the 2 models 2nd one is fine for me (using pipeline), because you avoid the iteration all you do is hitting del query for n times.
You can use del of multiple keys for every 100 or 1000 (whichever you feel as optimal after a small testing). You can group them to a pipeline altogether.
Or if you can do the same without atomicity, you can delete every 100 or 1000 keys at once in a loop, so that it wouldn't be a blocking call.
Try out with different combinations take the metrics and go with the optimized one.