Summary

mailbox timeouts and thread signaling

Metadata

• Id: 100f5e41c77929d53935feb6e3e8c4cd6cbb66ba
• Trac id: 1372
• Type: defect
• Reporter: caolan
• Owner: kon
• Cc:
• Status: assigned
• Component: extensions
• Estimated difficulty:
• Resolution:
• Priority: major
• Milestone: someday
• Version: 4.12.0
• Changetime: 2017-08-25 16:56:34 UTC
• Created: 2017-05-23 11:31:33 UTC
• Keywords: mailbox

Description

There appears to be a scheduler problem in the mailbox egg. If I signal a thread waiting on mailbox-receive! with a timeout, the program hangs and csi eats all my cpu.

 (use srfi-18 mailbox)
 
 (define mbox (make-mailbox))
 (define primordial (current-thread))
 
 (define t (thread-start! (lambda ()
                            (thread-sleep! 1)
                            (thread-signal! primordial 'example))))
 
 ;; this hangs forever and eats all my cycles (with timeout)
 (print (mailbox-receive! mbox 4))
 
 ;; this exits as expected with the 'example exception (no timeout)
 (print (mailbox-receive! mbox))

Changes and comments

[2017-08-25 15:09:43 UTC] sjamaan changed status from new to assigned

[2017-08-25 15:09:43 UTC] sjamaan set owner to kon

[2017-08-25 15:09:43 UTC] sjamaan wrote:

I also noticed that mailbox fails to install right now...

[2017-08-25 16:56:34 UTC] kon wrote:

The above sleeps the primodial thread. When no threads other than the primodial thread ('t' above not started) the primodial times-out. But w/ another thread to run the primodial is never timed-out; I need to look in the scheduler, sounds not right.

Suggest not doing a 'mailbox-receive!' while running as the primodial, at least for now.

Ex: 'reader-writer-test' uses a separate reader & writer threads.