Concurrent priority queue in redis?

redis queue
redis sorted set
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redis zset
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I would like to implement a concurrent priority queue in Redis, with multiple processes on different machines adding items (with scores) and multiple other processes popping these items, lowest score first.

A simple queue can be implemented with LPUSH and RPOP.

Using a ZSET, I can add the items using ZADD and pop them with ZRANGE and ZREM, as long as there is only one reader.

For multiple readers I think I need something like ZPOP which combines ZRANGE and ZREM in a single atomic operation. Otherwise two readers may get the same item from ZRANGE before either can ZREM it. Retrying if ZREM returns 0 would work but is not desirable.

Is there some way I can do this using the current Redis commands? Is there any reason this hasn't been added to Redis already? It seems like it would be a pretty simple command to implement.


You can guarantee atomicity if you use a Lua script that does the ZRANGE & ZREM or with a MULTI/EXEC block. This will prevent multiple workers from interfering with each other.

I assume that ZPOP wasn't put in in the first place because it isn't a common use case and, when needed, it can be easily scripted.

Priority queue in Redis aka ZPOP – Charles Nagy, Notice that we don't need any special locking or concurrency control because we check the return value of zrem command. If it managed to� Now you have a perfect priority queue implementation using basic redis commands. ZREM vs ZREMRANGEBYRANK. ZREM has the time complexity (quoting redio.io): O(M*log(N)) with N being the number of elements in the sorted set and M the number of elements to be removed. ZREMRANGEBYRANK’s time complecity:


you can use redis command: watch

WATCH zset
element = ZRANGE zset 0 0
MULTI
ZREM zset element
EXEC

if exec fails (return a null reply), just repeat those commands.

6.4.1 First-in, first-out queues, why, and will implement a worker process that can be run in parallel to send multiple If there are no high-priority items, then items in the medium-priority level� Concurrent priority queue in redis? 0. Redis Sorted Set Member Size and Performance. 0. Set options for ZADD command in laravel redis. 2. Redis sorted set based on


From Redis 5.0.0 you can use ZPOPMIN and ZPOPMAX (and their blocking counterpart BZPOPMIN and BZPOPMAX).

gabfl/redis-priority-queue: Simple Redis work queue with , redis-priority-queue is a simple work queue similar to Redis lists with the following added features: An item can be added with a priority (between -9007199254740992 and 9007199254740992) Queues are automatically de-duplicated (duplicate items are voided when pushing them) I ended up storing in <thread-specific-processing-queue> which is a redis z-set, and not a queue. So the expiry time is the score of the element in the z-set. Then I use redis scheduling pattern to scan the z-set based on score and then put back the expired keys to main queue. – Mopparthy Ravindranath Jul 28 '15 at 8:20


Distributed Java Queues on Top of Redis, Messages may be sent according to their age or according to some other predefined priority ranking. In order to store these pending messages,� Redis Connection Settings. By default, Kue will connect to Redis using the client default settings (port defaults to 6379, host defaults to 127.0.0.1, prefix defaults to q). Queue#createQueue(options) accepts redis connection options in options.redis key.


RPOPLPUSH – Redis, A simple form of queue is often obtained pushing values into a list in the producer side, with the smallest delay possible, using a number of parallel workers. REDIS_START_URLS_BATCH_SIZE : int (deprecated by CONCURRENT_REQUESTS) Default number of messages to fetch from redis on each attempt. REDIS_START_URLS_AS_SET : bool (default: True) Use SET operations to retrieve messages from the redis queue. REDIS_ENCODING : str (default: "utf-8") Default encoding to use when decoding messages from redis queue


BLPOP – Redis, Priority ordering details. If the client tries to blocks for multiple keys, but at least one key contains elements, the returned key / element pair is the first key from left � php artisan queue:table php artisan migrate Redis. In order to use the redis queue driver, you should configure a Redis database connection in your config/database.php configuration file. Redis Cluster. If your Redis queue connection uses a Redis Cluster, your queue names must contain a key hash tag. This is required in order to ensure all of