nonblocking | 易学教程

How to make non-blocking raw_input when using eventlet.monkey_patch() and why it block everything, even when executed on another thread?

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问题 I wrote this minimum code to explain my case: import threading import time import eventlet eventlet.monkey_patch() def printing_function(): while True: # here i want to do some work print "printing" time.sleep(1) if __name__ == '__main__': thread = threading.Thread(target=printing_function) thread.start() while True: # here i want to wait for users input raw_input("raw input\n") print "inside main loop" time.sleep(1) Even i have 2 threads, both of them are blocked when i call raw_input. When

Python Pyserial read data form multiple serial ports at same time

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问题 I'm trying to read out multiple serial ports at the same time with Python 2.7 and PySerial. Features should be: in the main program I get all open serial ports, open them and append the serial object to serialobjects I want to read each serial port data in one subprocess for parallelization The big problem is: how do I pass the serial port object to the subprocess? OR: Does another (and maybe better) solution exist to this? (Maybe this: How do I apply twisted serial ports to my problem?) EDIT

Should I use (non-blocking) NIO for UDP?

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问题 According to this post, UDP just doesn't block. Are there any advantage using the (non-blocking) NIO API for UDP? Or should I just use the easier "traditional" io API? 回答1: At the risk of just pointing you back, the comments to that post explain that UDP doesn't block on the TCP ACK, but you could still block on a kernel buffer overflow. This would happen only if you have a very big UDP burst. 回答2: If you are working with a large number of streams, it may help you to have a dedicate threading

MPI Non-blocking Irecv didn't receive data?

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I use MPI non-blocking communication(MPI_Irecv, MP_Isend) to monitor the slaves' idle states, the code is like bellow. rank 0: int dest = -1; while( dest <= 0){ int i; for(i=1;i<=slaves_num;i++){ printf("slave %d, now is %d \n",i,idle_node[i]); if (idle_node[i]== 1) { idle_node[i] = 0; dest = i; break; } } if(dest <= 0){ MPI_Irecv(&idle_node[1],1,MPI_INT,1,MSG_IDLE,MPI_COMM_WORLD,&request); MPI_Irecv(&idle_node[2],1,MPI_INT,2,MSG_IDLE,MPI_COMM_WORLD,&request); MPI_Irecv(&idle_node[3],1,MPI_INT,3,MSG_IDLE,MPI_COMM_WORLD,&request); // MPI_Wait(&request,&status); } usleep(100000); } idle_node

Can regular file reading benefited from nonblocking-IO?

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问题 It seems not to me and I found a link that supports my opinion. What do you think? 回答1: The content of the link you posted is correct. A regular file socket, opened in non-blocking mode, will always be "ready" for reading; when you actually try to read it, blocking (or more accurately as your source points out, sleeping) will occur until the operation can succeed. In any case, I think your source needs some sedatives. One angry person, that is. 回答2: I've been digging into this quite heavily

How do I check if an object is being @synchronized

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问题 Sometimes I wrote the following code to synchronized a routine: @synchronized(objToBeSync){ .... } When two threads try to access the sync block at the same time, one will block the others, until the one exits the sync block. However, sometimes I don't want one blocks the other, but the others check if the object is being synchronized, and then do some other thing so I have to do sth like this: @synchronized(objToBeSync){ _isBeingSync = YES; ... _isBeingSync = NO; } _isBeingSync is an

What is the difference between a blocking and non-blocking read?

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Add to the above question the concept of a wait/no wait indicator as a parameter to a ReadMessage function in a TCP/IP or UDP environment. A third party function description states that: This function is used to read a message from a queue which was defined by a previous registerforinput call. The input wait/no wait indicator will determine if this function will block on the queue specified, waiting for the data to be placed on the queue. If the nowait option is specified and no data is available a NULL pointer will be returned to the caller. When data available this function will return a

Is there an use case for non-blocking receive when I have threads?

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问题 I know non-blocking receive is not used as much in message passing, but still some intuition tells me, it is needed. Take for example GUI event driven applications, you need some way to wait for a message in a non-blocking way, so your program can execute some computations. One of the ways to solve this is to have a special thread with message queue. Is there some use case, where you would really need non-blocking receive even if you have threads? 回答1: Threads work differently than non

difference between blocking and non blocking statements with intra-assignment delay

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What is the difference between the following 2 snippets of verilog code? 1) always@(in) out = #5 in; AND 2) always@(in) out <= #5 in; Considering no other lines are present in the always block, can there be any difference in output? question is in reference to slide 16 (see o5 and o6 outputs) http://www.sutherland-hdl.com/papers/1996-CUG-presentation_nonblocking_assigns.pdf out = #5 in; blocks the next operation for 5 time units. It will prevent the monitoring of the next @(in) until the the 5 time units have passed. If you add a $display statement just before and after the assignment you will

Interrupt a connecting socket

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问题 I have a GUI with a list of servers to connect to. If a user clicks a server it connects to it. If a user clicks a second server, it will disconnect the first and connect to the second. Each new connection runs in a new thread so that the program can perform other tasks. However, if a user clicks a second server while the first is still connecting, there are two simultaneous connections. I'm connecting using this, and connect() is the line that blocks: Socket socket = new Socket(); socket