[NEMO-148] Decouple location request from actual data transfer

• Type: Sub-task
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Labels: runtime
• Assignee: Unassigned
• Reporter: John Yang
• Created: 08/Jul/18 07:04
• Updated: 09/Jul/18 05:52

Description

In BlockManagerWorker#readBlock, operations for (1) sending location request to the master, and (2) fetching data from a peer executor are chained with CompletedFuture#thenCompose.

  blockLocationFuture.thenCompose(responseFromMaster -> // chain

My concern is that it is not intuitive which thread executes this piece of code, and what that implies. My guess is that

1. Task executor thread request to the master
2. A network thread handles reply from the master
3. The network thread then triggers the data transfer

We may want to decouple 2. and 3., and instead use explicit threading.