Measuring Operational Times In Java Wall Clock

System nanotime we can use system nanotime to measure elapsed time with nanosecond precision.

Measuring operational times in java wall clock.

Instant start instant now. The reason is that no computer s clock is perfect. This is why nanotime is a great tool to measure the elapsed time between 2 events on a single jvm but we cannot compare timestamps from 2 different jvms. The instant and the duration classes.

Cplex setparam clocktype i in the net api. However solar days are not always equally long. There are 60 minutes on the clock so 360 divided by 60 minutes gives 6 per minute. Utc time scale actually allows a day to have 86 399 or 86 401 si seconds.

This will query the system clock to obtain the current time. You ll now see how to calculate elapsed time using two of the new java time types. Obtains the current time from the system clock in the specified time zone. Time passes instant end instant now.

Interactive optimizer with the command set clocktype i. Replace the i with the value 1 one to specify cpu time or 2 to specify wall clock time. Duration timeelapsed duration between start end. It is sometimes off and periodically needs to be corrected.

Clock was added in java 8 and provides access to an instant in time using the best available system clock and to be used as a time provider which can be effectively stubbed for testing purposes. Using this method will prevent the ability to use an alternate clock for testing because the clock is hard coded. 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. In this post we will discuss how to measure elapsed time in java using system nanotime system currenttimemillis instant now and stopwatch provided by guava and apache commons lang.

There are 12 hours on the clock so 360 divided by 12 hours gives 30 per hour. Specifying the time zone avoids dependence on the default time zone. Java time scale the traditional way of measuring time is to divide a day into 24 hours of 60 minutes of 60 seconds which gives 86 400 seconds a day. It returns the current value of the running jvm s high resolution time source in nanoseconds.

As these are designed for specific reasons it is important to choose the right one for your needs. The difference between two adjacent minutes is 6 degree. The purpose of nanotime is to measure elapsed time and the purpose of currenttimemillis is to measure wall clock time. Take a look at the following example.

The advantage is that even when wall clock time in a computer goes backwards for some reason it won t have any impact on nanotime.