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When to use the different log levels
...sysadmin wakes up, decides he's not paid enough for this, and goes back to sleep.
– Mateen Ulhaq
May 5 '17 at 18:53
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Singleton: How should it be used
...or just doesn't happen. If it does, the correct response is to go home and sleep for 12-20 hours and hope you feel better.
If only one object is needed, simply create one instance. If one object should be globally accessible, make it a global. But that doesn't mean it should be impossible to create...
Qt events and signal/slots
... select() call of the operating system. That call makes the application “sleep”, while it passes a bunch of sockets or files or whatever to the kernel asking for: if something changes on these, let the select() call return. – And the kernel, as the master of the world, knows when that happens....
Hidden Features of MySQL
...--------+------------------+
| 1 | root | localhost:32893 | NULL | Sleep | 0 | | NULL |
| 5 | system user | | NULL | Connect | 98 | Waiting for master to send event | NULL |
| 6 | system user | ...
deciding among subprocess, multiprocessing, and thread in Python?
...).
Basically it's all driven by the ability to make a request of the OS to sleep pending any activity on a list of file descriptors or some timeout.
Awakening from each of these calls to select() is an event --- either one involving input available (readable) on some number of sockets or file descri...
Start thread with member function
...i++)
{
cout << "CB()=" << i << endl;
Sleep(1000);
}
}
void main()
{
CB obj; // please note the address of obj.
thread t(obj); // here obj will be passed by value
//i.e. thread will make it own local copy of it.
...
multiprocessing.Pool: When to use apply, apply_async or map?
...mple:
import multiprocessing as mp
import time
def foo_pool(x):
time.sleep(2)
return x*x
result_list = []
def log_result(result):
# This is called whenever foo_pool(i) returns a result.
# result_list is modified only by the main process, not the pool workers.
result_list.appen...
What is Node.js? [closed]
...have been kicked off, the event function finishes and Node.js goes back to sleep. As soon as something else happens, like the database connection being established or the external server responding with content, the callback functions fire, and more JavaScript code executes, potentially kicking off ...
Context switches much slower in new linux kernels
...e light:
strace -r ./test_latency 0 1 &> test_latency_strace & sleep 8 && killall test_latency
then
for i in futex nanosleep rt_sig;do echo $i;grep $i test_latency_strace | sort -rn;done
which will show the microseconds taken for the interesting system calls, sorted by time....
How to measure time in milliseconds using ANSI C?
...fday(&tval_before, NULL);
// Some code you want to time, for example:
sleep(1);
gettimeofday(&tval_after, NULL);
timersub(&tval_after, &tval_before, &tval_result);
printf("Time elapsed: %ld.%06ld\n", (long int)tval_result.tv_sec, (long int)tval_result.tv_usec);
This returns...