Terracotta Discussion Forums (LEGACY READ-ONLY ARCHIVE)

Thanks for the tip.

Question:
Lets say I have four servers running in permanent-store mode, all with the same data directory and node0 is active and ten clients connected. If all clients asked for the same shared memory to read at the same time would the clients receive the data one at a time? The passive servers are not utilized in a situation where the read may take 5 seconds for each client? It seems to me passive servers are basically dead to the clients unless there is a network connection failure to the active server.

Thank you!

They would receive it in parallel from the active server - yes the passive's do not participate in these transactions.

Can you please explain how it does it in parallel? Since the server runs as one JVM I don't see how the JVM can concurrently transmit to each client.

I'm a system programming beginner. I do know that a processor can only run one thread at a time. The process in this case would be the JVM. My guess was that the server would create another thread and the processor would give one thread a time slice then switch to another thread for a time slice, etc. How would the server JVM transmit with many cores/processors available?

Thanks.

The number of threads that can run (actually) concurrently is determined by the number of processors/cores your hardware has.

In addition, processors are orders of magnitude faster than I/O - so it is very easy for a processor to send data to more than one client "at the same time" - while in reality it doesn't send the data to each node at exactly the same time it is in effect parallel due to the ability of the processor to do many things "at the same time" compared to the time of I/O.

When multiple processors are in play then multiple threads can run concurrently - but of course there is the system bus, the network card and so on that runs serially.