BoundedAsyncPool doesn't work with a negative maxTotal

[sguillope]

Bug Report

Current Behavior

When using the BoundedAsyncPool with a negative maxTotal, new pool objects are not created. Trying to acquire a new object will fail with io.lettuce.core.RedisException: java.util.NoSuchElementException: Pool exhausted

This can be reproduced by creating a pool with the following config:

BoundedPoolConfig.builder()
                .maxTotal(-1)
                .build();

Input Code

I've added 2 unit tests to BoundedAsyncPoolUnitTests based on the 5.2.x branch to demonstrate the failures:
https://github.com/lettuce-io/lettuce-core/compare/5.2.x...sguillope:bounded-async-pool-with-negative-max-total?expand=1

• shouldCreateObjectWhenMaxTotalIsNegative fails with

io.lettuce.core.RedisException: java.util.NoSuchElementException: Pool exhausted

	at io.lettuce.core.LettuceFutures.awaitAll(LettuceFutures.java:88)
	at io.lettuce.core.LettuceFutures.awaitAll(LettuceFutures.java:46)
	at io.lettuce.test.Futures.get(Futures.java:98)
	at io.lettuce.test.Futures.get(Futures.java:116)
	at io.lettuce.core.support.BoundedAsyncPoolUnitTests.shouldCreateObjectWhenMaxTotalIsNegative(BoundedAsyncPoolUnitTests.java:72)
	at ...
Caused by: java.util.NoSuchElementException: Pool exhausted
	at io.lettuce.core.support.BoundedAsyncPool.acquire()(Unknown Source)

• shouldCreateMinIdleObjectWhenMaxTotalIsNegative fails with

org.opentest4j.AssertionFailedError: 
Expecting:
 <0>
to be equal to:
 <2>
but was not.

Expected behavior/code

• Min number of idle objects are created based on the minIdle config when the pool is initialised
• New objects are created and returned by the pool when calling acquire()

Environment

• Lettuce version(s): 5.2.1.RELEASE
• Redis version: AWS Elasticache

Additional context

We found this issue after upgrading from SB 2.1 to 2.2.1 and to Spring Data Redis 2.2.1. We use the following Spring application.yml-based Redis config:

spring:
  redis:
    lettuce:
      pool:
        max-active: -1
        min-idle: 1
        max-idle: 10

When we upgraded our healthcheck (which include the redis component) started failing. Debugging found that java.util.NoSuchElementException: Pool exhausted was being thrown in RedisReactiveHealthIndicator.

[mp911de]

There's no support for -1 for maxTotal in BoundedPoolConfig. You're required to specify a max value, hence the name bounded pool. We have a utility (CommonsPool2ConfigConverter) that adapts a Commons Pool2 config to a BoundedPoolConfig. It would make sense to add a switch there to react to negative maxTotal settings and replace these with Integer.MAX_VALUE.

[sguillope]

Yeah I figured it might have been intended that way. Unfortunately the pool configuration declared through Spring's properties is used for both sync and async pools.

For now we've changed our max-active to a very high integer value to make it work. Automatically falling back to Integer.MAX_VALUE would work for us.

Thanks

[mp911de]

That's fixed now.