Is Duration Cpu Time Or Wall Clock Java

Changing the system time can affect the results or a leap second will disrupt the result.

Is duration cpu time or wall clock java.

Java8 stopwatch 100000000 6 666667e 11 0 5820 seconds 6 666667e 11 8 4530 seconds the code stopwatch data type is for measuring the time that. Execution time in nanoseconds. This clock is based on the best available system clock. The cpu time is measured in clock ticks or seconds.

Javac stopwatch java execution. Cpu time is the time that the barista spends making coffee it s the actual time spent performing work. Obtains a clock that returns the current instant using the best available system clock converting to date and time using the utc time zone. I ve always understood clock time to mean an instant not a duration.

Wall clock time cpu time unless you have multiple cpus ok well wall clock time in that context is new to me and on most charge reports i ve seen it was called elapse time. The current date and time depend on the time zone and for globalized applications a time provider is necessary to ensure that the date and time are created with the correct time zone. None a utility class to measure the running time wall clock of a program. However the result may and will be inaccurate as system currenttimemillis measures wall clock time.

Time elapsed is the difference between these two values. Now you maybe wondering why cpu time and wallclock time aren t the same number. The total time it takes for you to get a coffee including waiting to be served. Wall clock time is elapsed time the time on the clock on the wall.

After all your java process doesn t to have to wait in line at starbucks. Wall clock time may change for many reasons e g. The difference in wall and cpu time is rather large for this task clocking in at 35 237 seconds which was time sliced out to other processes. 5000372657 execution time in milliseconds.

System currenttimemillis java system class also provides the static method currenttimemillis that returns the difference between the current time and midnight january 1 1970 utc in milliseconds. Ideally currenttimemillis should be used to measure wall clock time. Often it is useful to measure cpu. Cpu time or process time is the amount of time for which a central processing unit cpu was used for processing instructions of a computer program or operating system as opposed to elapsed time which includes for example waiting for input output i o operations or entering low power idle mode.

The reason being is because of the time it takes to print over 50 000 files to the screen therefore the linux kernel s scheduler was free to give more time slices to other processes.