Blocked thread

Chris Angelico rosuav at gmail.com
Thu Jul 17 20:09:33 CEST 2014


On Fri, Jul 18, 2014 at 4:03 AM, Larry Martell <larry.martell at gmail.com> wrote:
> On Thu, Jul 17, 2014 at 2:01 PM, Chris Angelico <rosuav at gmail.com> wrote:
>> On Fri, Jul 18, 2014 at 3:55 AM, Larry Martell <larry.martell at gmail.com> wrote:
>>> I can have as many connections to the db server as I want, that's not
>>> the issue. The issue is that my main thread seems to be blocked in the
>>> join(), so I guess I'm going to need a separate script. I was trying
>>> to avoid that.
>>
>> Right, but what you're trying to do is monitor the local thread, by
>> spinning off a thread to do the deletion and then keeping an eye on it
>> by attempting a timed join. I'm saying it'd probably be easier to do
>> the monitoring on the server end, via a second connection. (It most
>> likely doesn't need special database privileges, even; at least in
>> PostgreSQL, any user can see pg_stat_activity entries for the same
>> user.) That's usually going to be more reliable, plus the server can
>> tell you whether the deletion is blocked waiting for a lock or busy
>> writing to the disk or something else.
>
> Yes, I agree, but the second connection will have to be in a second
> script, not the main thread of the script I have.

Maybe. I don't know what facilities Oracle gives you; it might be
possible to start a query asynchronously, with either a callback when
it's done or a poll for completion. Then another connection could be
used to keep an eye on the first one. But yes, doing it with a
completely separate script would be simpler in many ways. Or you might
be able to do the job with two threads.

ChrisA



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