timing

I want to know the time that it takes to execute a query in Postgres, I see a lot of response that propose to use \timing, but I'm newbie in Postgres and I don't know how to use it, can anyone help thank you in advance You can use \timing only with the command line client psql , since this is a psql command. It is a switch that turns execution time reporting on and off: test=> \timing Timing is on. test=> SELECT 42; ┌──────────┐ │ ?column? │ ├──────────┤ │ 42 │ └──────────┘ (1 row) Time: 0.745 ms test=> \timing Timing is off. 来源： https://stackoverflow.com/questions/40593723/how-to-use-timing

I want to measure the time of execution of an external program whose output is used by my Python script. Calling extprogram the program that produced the output, at the moment I do something like: import time import subprocess def process_output(line): ... ... return processed_data all_processed_data = [] ts = time.time() p = subprocess.Popen("extprogram", stdout=subprocess.PIPE) for line in p.stdout: all_processed_data.append(process_output(line)) te = time.time() elapsed_time = te - ts This doesn't work as intended because what I am measuring is the time of execution of extprogram plus the

I'm trying to time how long clock_gettime(CLOCK_REALTIME,...) takes to call. "Back in the day" I used to call it once at the top of a loop since it was a fairly expensive call. But now, I was hoping that with vDSO and some clock improvements, it might not be so slow. I wrote some test code that used __rdtscp to time repeated calls to clock_gettime (the rdtscp calls went around a loop that called clock_gettime and added the results together, just so the compiler wouldn't optimize too much away). If I call clock_gettime() in quick succession, the length of time goes from about 45k clock cycles

I have a thread running on a Linux system which i need to execute in as accurate intervals as possbile. E.g. execute once every ms. Currently this is done by creating a timer with timerfd_create(CLOCK_MONOTONIC, 0) , and then passing the desired sleep time in a struct with timerfd_settime (fd, 0, &itval, NULL); A blocking read call is performed on this timer which halts thread execution and reports lost wakeup calls. The problem is that at higher frequencies, the system starts loosing deadlines, even though CPU usage is below 10%. I think this is due to the scheduler not waking the thread

I'm posing this question mostly out of curiosity. I've written some code that is doing some very time intensive work. So, before executing my workhorse function, I wrapped it up in a couple of calls to time.clock(). It looks something like this: t1 = time.clock() print this_function_takes_forever(how_long_parameter = 20) t2 = time.clock() print t2 - t1 This worked fine. My function returned correctly and t2 - t1 gave me a result of 972.29 , or about 16 minutes. However, when I changed my code to this t1 = time.clock() print this_function_takes_forever(how_long_parameter = 80) t2 = time.clock()