Applications will hang during some IO operations while external HDD is leaving idle mode

Originator:taiki.mmt
Number:rdar://19135925 Date Originated:December 4 2014
Status:Open Resolved:
Product:macOS + SDK Product Version:10.10.0+
Classification:Crash/Hang/Data Loss Reproducible:Always
 
Summary:
While performing some disk related operations (opening an app/a prompt to [save | open] a file [to | from] disk), most of applications will hang while the external hard drive is leaving leaving idle mode and kicking in. This HDD contain my Time Machine if relevant.

The reproducibility rate hit 100% with the page save prompt in Safari

Steps to Reproduce:
1. Plug a external HDD
(2. Set up time machine on it?)
3. Wait for the energy saving policy to kick in
4. Make a operation requiring access from the UI to the eHDD

Expected Results:
Hang only when the disk is actually required, and display a loading message instead of a hang

Actual Results:
Applications hangs as a whole (can't do anything requiring IO meanwhile)

Version:
OSX 10.10.0+
Reproductible on 14C68k

Notes:
The problem probably come from a Cocoa API, and the hang from the applications making those lengthy call in the main thread. However, it'd be great if the prompt could appear before the eHDD is fully started, and would only be grayed out while accelerating.

Configuration:
MBPr with SSD
External HDD is a 7200 rpm disk

Comments


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