I m using Room Database along with their coroutines support

Question

I m using Room Database along with their coroutines support for managing the DB in my app and I m doing lots of queries in transaction since they span multiple relationships I noticed that they use a thread pool of 4 threads to execute queries there however this causes some long loading times due to queries being queued until one of the 4 threads is free to continue executions I thought about customizing the Query executor by providing `<http Dispatchers IO|Dispatchers IO> asExecutor ` but I m wondering if that would be an appropriate solution since as far as I learned `Dispatchers Default` shares some threads from IO and that might cause another set of problems So the question is would that be a good solution to the problem from multi threading perspective

Ahmed Ibrahim · Answer

I also started seeing from the logs ```Long monitor contention with owner DefaultDispatcher worker 6 27719 at android database sqlite SQLiteConnection android database sqlite SQLiteConnectionPool waitForConnection java lang String int android os CancellationSignal SQLiteConnectionPool java 1 waiters=0 in void android database sqlite SQLiteConnectionPool closeAvailableNonPrimaryConnectionsAndLogExceptions for 2 511s``` However not sure if I should ignore them

Ahmed Ibrahim · Answer

Not sure TBH if this question should stay in < C1CFAFJSK|coroutines> or moved to < C0B8M7BUY|android>

gildor · Answer

What kind set of problems could be caused by the fact that Default and IO share thread pool

gildor · Answer

Why do you need a special thread pool for Room isn t it already provide coroutine api and it uses IO under the hood

Ahmed Ibrahim · Answer

gt What kind set of problems could be caused by the fact that Default and IO share thread pool I m not entirely sure but perhaps since Default executor is supposed to be limited by the number of CPU core it might suffer from thread starvation issues as the IO would consume from Default s pool I might ve gotten that wrongly though gt Why do you need a special thread pool for Room isn t it already provide coroutine api and it uses IO under the hood It provides suspending calls but it uses their own dispatchers as per link which by default is a

bdawg.io · Answer

They SHARE a pool but manage their limits independently So default will have its thread limit available even if the maximum number IO threads are actively in use

gildor · Answer

As Bradyn said you also can configure IO and Default pools independently