Is Duration Cpu Time Or Wall Clock Java

Cpu time is not wall time as in a clock on the wall.

Is duration cpu time or wall clock java.

Long finishtime system currenttimemillis. Elapsed real time real time wall clock time or wall time is the actual time taken from the start of a computer program to the end. The wall clock time is 9 seconds. In other words it is the difference between the time at which a task finishes and the time at which the task started.

Clock clocktick clock tick clockdefaultzone duration ofseconds 30. System currenttimemillis measures elapsed physical time wall clock time not cpu time. The cpu time is measured in clock ticks or seconds. Cpu time is time spent in the cpu doing actual work as opposed to waiting or not being scheduled.

Long starttime system currenttimemillis. Wall clock time cpu time unless you have multiple cpus. If other applications are running on the machine your code will get less cpu and its speed will decrease. Long days timeunit milliseconds todays duration.

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 cpu time spent is 8 seconds 5 seconds for cpu 1 and 2 seconds followed by 1 second for cpu 2. It used to be chargeable that s why it was tracked separately. String diff millistoshortdhms finishtime starttime.

Often it is useful to measure cpu. As suggested by others system currenttimemillis is quite good but note the following caveats. Wall clock time is elapsed time the time on the clock on the wall. Wall time is thus different from cpu time which measures only the time during which the processor is actively working on a certain task.

Clock clockdefaultzone clock systemdefaultzone. The cpu must service many processes every second not just yours so your process only gets small task slices in between processing other requests. Cpu time is the total execution time or runtime for which the cpu was dedicated to a process. So bench only on otherwise idle systems.

Scea part 1 part 2 3 core spring 3 togaf part 1 and part 2. The specified clock duration must be positive.