I am using coroutines on Google App Engine. I have...

# coroutines

[rahulrav]

I am using coroutines on Google App Engine. I have a coroutine dispatcher which uses the defined executor:

private fun defaultExecutor(): ThreadPoolExecutor {
    val maxPoolSize = Runtime.getRuntime().availableProcessors() * 3
    val keepAliveTime = 2L // in seconds
    val queue = LinkedBlockingQueue<Runnable>()
    return ThreadPoolExecutor(0, maxPoolSize, keepAliveTime, TimeUnit.SECONDS, queue, ThreadManager.currentRequestThreadFactory())
  }

Note the use of the ThreadManager.currentThreadRequestFactory().

Every time I invoke a suspend function I ensure that it is accompanied by a withContext(...) which uses the above defined coroutine dispatcher.

I see that sometimes, I get `Exception`s on App Engine, claiming I am trying to get an instance of supporting services (like Datastore or Memcache) on a thread which was not created by their thread factory (ThreadManager). This typically happens in a coroutine's resume method. Any ideas on what I might be doing wrong ?

[elizarov]

I cannot Google currentThreadRequestFactory. Can you given a link to its docs?

[louiscad]

@elizarov https://cloud.google.com/appengine/docs/standard/java/javadoc/com/google/appengine/api/ThreadManager

[elizarov]

So it says Returns a ThreadFactory that will create threads scoped to the current request.

[elizarov]

It seems that you creating it in one request and reusing in another request

[louiscad]

@rahulrav I think you should do the (inefficient but seemingly required) approach:
withContext(ThreadManager.currentRequestThreadFactory()) { ... /* Code accessing to the supporting services like Memcache or Datastore. */ }

[rahulrav]

That makes sense. Thanks folks