CPU profiling for rescue

Prev – Test on smaller data set

I use Eclipse editor for my development since many years and couple of years ago I had looked for good CPU profiling plugins for Eclipse and had not found one, since then just for profiling java code, I use NetBeans editor as it had in-built support for CPU and Memory profiling. I started NetBeans for carrying out CPU profiling and for some unknown reasons, I was just not able to profile my JUnit test suite in NetBeans. Since I use NetBeans just for profiling, I have to keep doing lot of setup on it, which I hate, and now I also had to figure out why the profiling was not running. I had no patience to figure it out, instead I attempted to check if there are any new profiling plugins available for Eclipse and I came across JVM Monitor and boy, now I am loving it!

Profiling our tests highlighted following issues in our code.

  • The code was scanning resource bundle files, a disk IO intensive operation, multiple time. I just cached them.
  • Many tests were loading the spring file system application context. Some tests were doing it in the @Before method, causing the context to be loaded before every test method in that class. This is again a disk IO intensive operation. After some refactoring of the test code, I could reuse the context in majority of the tests.
  • Our code was sending out emails during our tests, which was taking time and not required. I skipped sending out emails.
  • There was a class which was accepting a java Date object and the number of days to be added to the date. Code snippet below. This method was invoked thousands of time.

public static Date addDays(Date date, int numberOfDays)


Calendar  calendar  = Calendar.getInstance();


calendar.add(Calendar.DATE, numberOfDays);

return calendar.getTime();


To my surprise, this simple looking code is not efficient at all. I refactored the code as below and it is much more efficient.

public static Date addDays(Date date, int numberOfDays)


long number = ((long)numberOfDays) *MILLISECONDS_IN_ONE_DAY;

return new Date(date.getTime() + number);


After all the profiling and refactoring, most of the test jobs started getting over within 15 minutes. Without using SSDs/Hybrid disks, I was able to get the CI build pipeline time down to about 25 minutes. Now it is not a surprise as to why the RAM Drives did not show much improvement on our actual Jenkins. Disk IO not related to the DB was our bottleneck. So though SSDs are fast, it turns out that SSDs are not alternatives for sloppy programming! lol.

Next – On a quest of reducing Jenkins build time.



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