Maybe UD is where I am remembering this from.

On 10/24/2011 4:19 PM, Dave Davis wrote:
I don't know about UV but in UD, LIST.QUEUE shows waiters.

-----Original Message-----
From: u2-users-boun...@listserver.u2ug.org 
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles Stevenson
Sent: Monday, October 24, 2011 5:12 PM
To: U2 Users List
Subject: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o 
explicit readu.

UV 10.2.10 on Windows is behaving differently from what I recall.
Are my expectations out of line?

Suppose Session A holds a readu lock; and Session B attempts a WRITE to
same record withOUT!!! 1st explicitly getting the readu lock.
Session B waits for Session A to release the lock before writing the record.

While Session B is waiting,  does it show up as a "waiter" in LIST.READU
EVERY?
I expected so,  but it doesn't.


Session A                       Session B
_____________________________   ___________________
1A. ED VOC DUMMY
     (this sets the readu lock.)

2A. (stay in editor)            2B. run this:
                                      01:    OPEN 'VOC' TO F ELSE STOPM
'nope'
                                      02: ***READU REC FROM F, 'DUMMY'
ELSE NULL
                                      03:    WRITE '' TO F, 'DUMMY'

3A. Within ED:
      XEQ LIST.READU EVERY


If I UN-comment line 2, LIST.READU EVERY shows something like this:

      Active Read Waiters:      Owner   Waiter
      Device....  Inode....     Userno  Userno
      746117947    232860913      6116    3396


But when I comment out line 2, LIST.READU is silent.
I have not yet explored what the deadlock daemon does.

TIA,
cds


P.S. Yes, yes, "Bad Form", "Legacy Software", 20 min wait is
configurable, . . . we can talk later.
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