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 writi
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
: u2-users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles
Stevenson
Sent: Monday, October 24, 2011 2:12 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 differen
.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles
Stevenson
Sent: Monday, October 24, 2011 2:12 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
-
From: u2-users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles Stevenson
Sent: Tuesday, 25 October 2011 8:12 AM
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 Wind
users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Mecki
Foerthmann
Sent: Monday, October 24, 2011 3:30 PM
To: u2-users@listserver.u2ug.org
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are
writes w/o explicit readu.
Now why would anybody want
;t say I
liked the idea
-Original Message-
From: u2-users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Mecki
Foerthmann
Sent: Monday, October 24, 2011 3:30 PM
To: u2-users@listserver.u2ug.org
Subject: Re: [U2] [UV] LIST.READU EVERY's "waite
un...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles
Stevenson
Sent: Monday, October 24, 2011 2:12 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 behavin
g.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles
Stevenson
Sent: Monday, October 24, 2011 2:12 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 wha
enson
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
the idea
-Original Message-
From: u2-users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Mecki
Foerthmann
Sent: Monday, October 24, 2011 3:30 PM
To: u2-users@listserver.u2ug.org
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" wh
WRITEU, too. Didn't say I
liked the idea
-Original Message-
From: u2-users-boun...@listserver.u2ug.org
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Mecki
Foerthmann
Sent: Monday, October 24, 2011 3:30 PM
To: u2-users@listserver.u2ug.org
Subject: Re: [U2] [UV] LI
Why the 'deadly embrace' issue
From: Wjhonson
To: u2-users@listserver.u2ug.org; sfr192...@yahoo.com
Sent: Monday, October 24, 2011 8:42 PM
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
s w/o
explicit readu.
Why the 'deadly embrace' issue
From: Wjhonson
To: u2-users@listserver.u2ug.org; sfr192...@yahoo.com
Sent: Monday, October 24, 2011 8:42 PM
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
Yes.
Today, deadly embraces can be avoided via LOCKED clauses.
In days of yore, Pick's READU syntax did not allow a LOCKED clause.
BTW, I advocate 2 Programming Standards:
1. If a lock is taken (READU, RECORDLOCKU, FILELOCK, etc.), a
LOCKED clause must be present.
2. A lock must be se
Deadly Embraces cannot be avoided by use of a LOCKED clause.
That's not what it means.
-Original Message-
From: Charles Stevenson
To: U2 Users List
Sent: Tue, Oct 25, 2011 6:29 am
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes
What if you were writing to an empty file?
Rich
- Original Message -
From: "Mecki Foerthmann"
To: u2-users@listserver.u2ug.org
Sent: Monday, October 24, 2011 6:30:08 PM
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit read
This is deadly embrace
http://knol.google.com/k/will-johnson/deadly-embrace-on-pick-systems/4hmquk6fx4gu/816#view
The Locked clause does not save us from it. There is no known trivial solution
to the problem, which troubles all multi-table, multi-user database
environments.
Perhaps we should
hat if you were writing to an empty file?
Rich
- Original Message -
From: "Mecki Foerthmann"
To: u2-users@listserver.u2ug.org
Sent: Monday, October 24, 2011 6:30:08 PM
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
N
Oh yes there is a very easy solution.
If you write a mass update process like in your example you skip the
records with a lock and write them to an error log file.
That way you never end up in a "deadly embrace".
After you finished the mass update you can then check for skipped
records and upda
s will let you
know quite clearly with loud noises and waving of arms.
-Original Message-
From: Mecki Foerthmann
To: u2-users
Sent: Tue, Oct 25, 2011 10:58 am
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
Oh yes there i
-
From: Mecki Foerthmann
To: u2-users
Sent: Tue, Oct 25, 2011 10:58 am
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
Oh yes there is a very easy solution.
f you write a mass update process like in your example you skip the
eco
I know I'll write a phantom to monitor the phantom and write an error log read
by a third phantom!
I'll be at the top of the matrix in six years!
___
U2-Users mailing list
U2-Users@listserver.u2ug.org
http://listserver.u2ug.org/mailman/listinfo/u2-user
You could do it all in one program and run only one phantom, but of
course you can make it a lot more difficult if you want too.
KISS
On 25/10/2011 20:13, Wjhonson wrote:
I know I'll write a phantom to monitor the phantom and write an error log read
by a third phantom!
I'll be at the top of
ubject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
You could do it all in one program and run only one phantom, but of
ourse you can make it a lot more difficult if you want too.
ISS
n 25/10/2011 20:13, Wjhonson wrote:
I know I'll
On 10/24/2011 4:11 PM, Charles Stevenson wrote:
--- [snip] ---
I have not yet explored what the deadlock daemon does.
Deadlock daemon ignores these WRITEs w/o explicit locking before hand.
I ran these 2 pgms simultaneously so that they both tried to lock or
write the lock that the other held.
n
To: U2 Users List
Sent: Tue, Oct 25, 2011 3:12 pm
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
On 10/24/2011 4:11 PM, Charles Stevenson wrote:
--- [snip] ---
I have not yet explored what the deadlock daemon does.
Deadlock daemon
But if there is explicit READUs in both processes, that one of them will fail
in 20 minutes?
-Original Message-
From: Charles Stevenson
To: U2 Users List
Sent: Tue, Oct 25, 2011 3:12 pm
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explic
nt: Tue, Oct 25, 2011 4:15 pm
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
English is my 1st language, but that doesn't mean I'm good at it.
et me try again.
1. If either (or both) of these have WRITEs without explicit rea
nation, but you can't avoid deadlocks with LOCKED
clauses.
Maybe what you meant was something like "You can try to think of some strategy to
deal with them when they occur."
-Original Message-
From: Charles Stevenson
To: U2 Users List
Sent: Tue, Oct 25, 2011 4:15 pm
Subje
While Will's articledoes give a good, clear example of a deadly embrace,
and remediating faulty code is not trivial, the solution is conceptually
trivial and it is exactly the LOCKED clause that saves us.
If you write new code, deadlocks are easy to prevent.
Testing is non-trivial. It generall
five minutes
of typing without so much as a "by your leave" ?
He is going to be very mad at you for that.
-Original Message-
From: Charles Stevenson
To: U2 Users List
Cc: Wjhonson
Sent: Tue, Oct 25, 2011 5:21 pm
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters&q
It is not possible to know in advance all the locks you may wish to set.
That's the problem.
-Original Message-
From: Charles Stevenson
To: U2 Users List
Sent: Tue, Oct 25, 2011 5:22 pm
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes
ow in advance all the locks you may wish to set.
That's the problem.
-Original Message-
From: Charles Stevenson
To: U2 Users List
Sent: Tue, Oct 25, 2011 5:22 pm
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
While Will&
Accountants... How about a ER doc waiting on lab results for cardiac enzymes? I
can hear it now: "Sorry Doc, something else locked the record. Your patient's
test request was skipped so we could implement a trivial solution that was
suggested for deadly embrace. Try again, and hope for the best
Come on, get real.
Do you suggest the "deadly embrace" would be better and he would get his
results any quicker?
And anyway, an ER doc not getting his lab results because of a mass
update process running as a phantom encountering a locked record?
And who would hold a lock on those lab results
I'm "suggesting" that blinding skipping records is a HORRIBLE idea, and in our
case, potentially life threatening - literally. You need to get real with your
suggestion that coding for deadly embrace situations is a "very easy solution"
(your words). Not every phantom is a mass update. The IS r
I never said anything about blindly (I guess that's what you meant)
skipping records.
I suggested writing the locked record ids somewhere else and process
them later for Wills not necessarily life-threatening sales rep update
phantom.
I at least don't feel threatened by accountants.
If somebody
On 10/26/2011 7:45 AM, Robert Porter wrote:
Accountants... How about a ER doc waiting on lab results for cardiac
enzymes? I can hear it now: "Sorry Doc, something else locked the
record. Your patient's test request was skipped so we could implement
a trivial solution that was suggested for dead
I hate to bring it up after 50+ responses over 4 days, but . . .
Did anyone ever actually run my little test?
On something other than my UV10.2/Win? Unix? Before UV10.2?
Knowing that would help me assess the size & age of our problem.
I still think that in times past, a waiterfor a lockvia
: Charles Stevenson
Cc: U2 Users List
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
I hate to bring it up after 50+ responses over 4 days, but . . .
Did anyone ever actually run my little test?
On something other than my UV10.2/Win?
:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles Stevenson
Sent: Sunday, 30 October 2011 10:22 AM
To: Charles Stevenson
Cc: U2 Users List
Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o
explicit readu.
I hate to bring it up after 50+ respon
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