Redis exception: Cannot use Jedis when in Multi.

Jedis newbie problem when adding transactions to Redis client application:

Cannot use Jedis when in Multi. Please use JedisTransaction instead.
redis.clients.jedis.exceptions.JedisDataException: Cannot use Jedis when in Multi. Please use JedisTransaction instead.
 at redis.clients.jedis.BinaryJedis.checkIsInMulti(BinaryJedis.java:1651)
 at redis.clients.jedis.Jedis.hmset(Jedis.java:724)
 at test.TestService.updateSomething(TestService.groovy:39)
 at test.TestService$_processBet_closure1.doCall(TestService.groovy:16)
 at grails.plugin.redis.RedisService.withRedis(RedisService.groovy:67)

Description of exception is absolutely correct though a little confusing. Problem is that you are trying to call methods on Redis connection object instead of Transaction object. So most probably you have something like:

  Jedis jedis = pool.getResource()
  jedis.watch('foo')
  ...
  def transaction = jedis.multi()
  jedis.set("foo", value.toString())
  def result = transaction.exec()

But instead, you should have something like:

  Jedis jedis = pool.getResource()
  jedis.watch('foo')
  ...
  def transaction = jedis.multi()
  transaction.set("foo", value.toString())
  def result = transaction.exec()