Review for Quiz 2 of COMP 310

Review for Quiz 2 of COMP 310 - Review for Quiz 2 1 Chapter...

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Review for Quiz 2: 1. Chapter 3: Processes Starting from slide 3.37 inter-process communication mailbox sharing solutions link: only two processes? only one process can execute receive operation at a time? round-robin scheme - sender throws it out randomly, some receiver gets it, sender gets notified as to who message passing: blocking or not, on part of sender or receiver queue of messages attached to link zero capacity: sender waits for receiver (rendez-vous) bounded (finite) capacity: sender waits if queue full unbounded (infinite) capacity: sender never waits, is this even possible? Examples POSIX shared memory process creates shared memory segment, returns an ID processes wanting access to that segment must attach to it by ID (call returns pointer) can write to that memory segment (using the pointer) can detach it from its address space when done Mach: message-based (everything! even system calls) all tasks are created with 2 mailboxes (which are created with port_allocate(): kernel, and notify three system calls: msg_send, msg_receive, msg_rpc (remote procedure call, to execute something elsewhere) Windows XP: message-based using "local procedure call" (can only be used by local processes) communication channels established using ports (sort of like mailboxes) client opens handle to subsystem's connection port, sends a connect request server creates two private communication ports, sends one to client, keeps the other one corresponding ports are used by server and client to send/receive messages INSERT DIAGRAM LATER client-server communication sockets (endpoints for communication) IP address + port different services listen on different ports, e.g. ssh on 22, typical web servers on 80, etc
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remote-procedure calls allows clients to invoke a procedure on a remote host as if it were local client-side stub locates server, marshalls parameters, sends them over (underlying details abstracted) server-side stub receives messages, unmarshalls parameters, performs procedure INSERT DIAGRAM LATER (or describe it at least) remote method invocation (java only) java program on one machine can call a method on a remote java object basically the same as RMI except there are objects involved THERE IS A DIAGRAM HERE. it doesn't really say much though. look it over anyway 2. Chapter 4: Threads Thread: unit of CPU utilisation, forms basis of multithreaded computers things unique to each thread: thread ID, program counter, register set, stack things threads from the same process share: code, data (statically-created variables), OS resources (open files, signals) single-threaded process: code + data + files, then registers + stack multi-threaded: code + data + files, then each thread gets its own registers and stack Benefits of threading
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