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What is a memory fence?
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For performance gains modern CPUs often execute instructions out of order to make maximum use of the available silicon (including memory read/writes). Because the hardware enforces instructions integrity you never notice this in a single thread of execut...
Difference between java.util.Random and java.security.SecureRandom
... - In case of random just 2^48 attempts are required, with todays advanced cpu's it is possible to break it in practical time. But for securerandom 2^128 attempts will be required, which will take years and years to break even with today's advanced machines.
See this link for more details.
EDIT
A...
Does async(launch::async) in C++11 make thread pools obsolete for avoiding expensive thread creation
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And native, on my MacBook Pro 15" (Intel(R) Core(TM) i7-7820HQ CPU @ 2.90GHz) with Apple LLVM version 10.0.0 (clang-1000.10.44.4) under OSX 10.13.6, I get this:
Do nothing calls per second: 22078079
Empty calls per second: 21847547
New thread calls per second: 433...
If vs. Switch Speed
...complex but basically boils down to the table indirection neutering modern cpu jump target buffers and so wipes out the branch predictor. I vaguely recall a paper at a GCC conference on codegen for switches.
– olliej
Jan 14 '09 at 23:46
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What is the difference between JDK and JRE?
...va), the sole purpose of which is to run as fast as possible on the target CPU (virtual CPU of your JVM). Java code gets converted into several machine code instructions. Variables are shoved all over the place – into the stack, into registers, or completely optimized away. Structures and objects ...
Reading binary file and looping over each byte
...orming but easily understandable code can be much preferred. The waste of CPU cycles is compensated for saving "reader CPU cycles" when maintaing the code.
– IllvilJa
Feb 5 '19 at 9:37
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When do I need to use AtomicBoolean in Java?
...of threads running through your
critical sections, a substantial
amount of CPU time is spent in
managing the synchronization
mechanism itself (waiting, notifying,
etc). Since the new API uses hardware
level constructs (atomic variables)
and wait and lock free algorithms to
implement thread-safety, a...
PHP memory profiling
... like shown below:
Xhprof + Xhgui (the best in my opinion to profile both cpu and memory)
With Xhprof and Xhgui you can profile the cpu usage as well or just the memory usage if that's your issue at the moment.
It's a very complete solutions, it gives you full control and the logs can be written bo...
Does Python support multithreading? Can it speed up execution time?
...tween threads.
What the GIL prevents then, is making use of more than one CPU core or separate CPUs to run threads in parallel.
This only applies to Python code. C extensions can and do release the GIL to allow multiple threads of C code and one Python thread to run across multiple cores. This ext...
What's a good rate limiting algorithm?
...ng, you definitely do not want to use time.clock(), which measures elapsed CPU time. CPU time can run much faster or much slower than "actual" time. You want to use time.time() instead, which measures wall time ("actual" time).
– John Wiseman
Dec 21 '15 at 23...