AsyncLimitUsageStorage memory leak in high concurrency situation

[xiongshilin]

the call method 'AsyncLimitUsageStorage.addAndGet' occur memory leak, this will create too manay tasks in high concurrency situation, but there is only one thread that executes task to send data to distribute storage, so more and more tasks will be kept in long stock.

[Sytten]

You should consider using the batched storage in this case then. It will be less accurate, but it's a trade-off. Trying to increase the number of threads to send the data is likely to cause concurrency problems with the current implementation. We should add a note in the readme about this.

[Sytten]

If you have time to improve it: #21