Is it OK for multiple threads to use the same PrintWriter concurrently?
Jul 17 '05
11  8444 
"Jeff Schwab" <je******@comca st.net> wrote in message
news:FK******** ************@co mcast.com... Silvio Bierman wrote: "Jeff Schwab" <je******@comca st.net> wrote in message
news:Qa******** ************@co mcast.com...
Yes, if necessary, I'll do that. I expect to have hundreds or thousands
of threads at a time vying for the same Writer, though, and I worry that
the performance detriment will be too great.
Is it safe to get the current time simultaneously in different threads,
without synchronization ? I only need to see error messages immediately
when the app ( a server ) is first starting. Once things get going,
it's just the order of the messages that needs to be preserved. Maybe I
could use the message-queue idea, and add time-stamps to the messages.
What do you think?
You have that many threads shortly after starting your server?
Impressive!
:) Not usually, but I have to be prepared for it.
Using a synchronized queue would work fine and it would probably mean
less time lost due to synchronization when compared to synchronzied
println's. Your print-thread would be wait-ing on the queue and the error producers
would have to notify it to start the printing. The simpler alternative
would be using a timed wait but that would delay error logging and activate
the printing thread even when no messages are present.
Thanks, Silvio, sounds good. Does this mean that PrintWriter isn't
synchronized on its own, or does this mean that we don't know, so I
should do possibly redundant synchronization just to make sure?
You could probably wrap such a thing inside a
SynchronizedQue uePrintStream and use System#setErr to prevent code modifications.
What is "System#setErr" ?
Let me see, 8,000 threads. If each thread tries to print a single 50
character
message once per minute you will have 576,000,000 bytes of data in one day.
How bout using the logging capability?
nos wrote: "Jeff Schwab" <je******@comca st.net> wrote in message
news:FK******** ************@co mcast.com...
Silvio Bierman wrote:
"Jeff Schwab" <je******@comca st.net> wrote in message
news:Qa***** *************** @comcast.com...
Yes, if necessary, I'll do that. I expect to have hundreds or thousands
of threads at a time vying for the same Writer, though, and I worry that
the performance detriment will be too great.
Is it safe to get the current time simultaneously in different threads,
without synchronization ? I only need to see error messages immediately
when the app ( a server ) is first starting. Once things get going,
it's just the order of the messages that needs to be preserved. Maybe I
could use the message-queue idea, and add time-stamps to the messages.
What do you think?
You have that many threads shortly after starting your server?
Impressive!
:) Not usually, but I have to be prepared for it.
Using a synchronized queue would work fine and it would probably mean
less
time lost due to synchronization when compared to synchronzied
println's.
Your print-thread would be wait-ing on the queue and the error producers
would have to notify it to start the printing. The simpler alternative
would
be using a timed wait but that would delay error logging and activate
the
printing thread even when no messages are present.
Thanks, Silvio, sounds good. Does this mean that PrintWriter isn't
synchronize d on its own, or does this mean that we don't know, so I
should do possibly redundant synchronization just to make sure?
You could probably wrap such a thing inside a
SynchronizedQue uePrintStream
and use System#setErr to prevent code modifications.
What is "System#setErr" ?
Let me see, 8,000 threads. If each thread tries to print a single 50
character
message once per minute you will have 576,000,000 bytes of data in one day.
How bout using the logging capability?
Where did you come up with your data? I never said 8000 threads all the
time. More like 3000 at a time in short bursts, when a bunch of people
hit a web site. I need the messages to be ordered for debugging purposes. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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