Why is printing B dramatically slower than printing

Question

I generated two matrices of 1000 x 1000   First Matrix  O and    Second Matrix  O and B   Using the following code  the first matrix took 8 52 seconds to complete   Random r   new Random    for  int i   0  i  lt  1000  i          for  int j   0  j  lt  1000  j              if r nextInt 4     0                System out print  O              else               System out print                           System out println           With this code  the second matrix took 259 152 seconds to complete   Random r   new Random    for  int i   0  i  lt  1000  i          for  int j   0  j  lt  1000  j              if r nextInt 4     0                System out print  O              else               System out print  B      only line changed                      System out println          What is the reason behind the dramatically different run times     As suggested in the comments  printing only System out print       takes 7 8871 seconds  whereas System out print  B    gives still printing      As others who pointed out that it works for them normally  I tried Ideone com for instance  and both pieces of code execute at the same speed   Test Conditions    I ran this test from Netbeans 7 2  with the output into its console I used System nanoTime   for measurements

User · Accepted Answer

Pure speculation is that you re using a terminal that attempts to do word-wrapping rather than character-wrapping  and treats B as a word character but   as a non-word character  So when it reaches the end of a line and searches for a place to break the line  it sees a   almost immediately and happily breaks there  whereas with the B  it has to keep searching for longer  and may have more text to wrap  which may be expensive on some terminals  e g   outputting backspaces  then outputting spaces to overwrite the letters being wrapped    But that s pure speculation

User · Answer

I performed tests on Eclipse vs Netbeans 8 0 2  both with Java version 1 8  I used System nanoTime   for measurements  Eclipse  I got the same time on both cases - around 1 564 seconds  Netbeans   Using  quot   quot   1 536 seconds Using  quot B quot   44 164 seconds  So  it looks like Netbeans has bad performance on print to console  After more research I realized that the problem is line-wrapping of the max buffer of Netbeans  it s not restricted to System out println command   demonstrated by this code  for  int i   0  i  lt  1000  i          long t1   System nanoTime        System out print  quot BBB      BBB quot       lt -contain 1000  quot B quot      long t2   System nanoTime        System out println t2-t1       System out println  quot  quot       The time results are less then 1 millisecond every iteration except every fifth iteration  when the time result is around 225 millisecond  Something like  in nanoseconds   BBB   31744 BBB   31744 BBB   31744 BBB   31744 BBB   226365807 BBB   31744 BBB   31744 BBB   31744 BBB   31744 BBB   226365807        And so on   Summary   Eclipse works perfectly with  quot B quot  Netbeans has a line-wrapping problem that can be solved  because the problem does not occur in eclipse  without adding space after B   quot B  quot

User · Answer

Yes the culprit is definitely word-wrapping  When I tested your two programs  NetBeans IDE 8 2 gave me the following result    First Matrix  O and     6 03 seconds Second Matrix  O and B   50 97 seconds   Looking at your code closely you have used a line break at the end of first loop  But you didn t use any line break in second loop  So you are going to print a word with 1000 characters in the second loop  That causes a word-wrapping problem  If we use a non-word character     after B  it takes only 5 35 seconds to compile the program  And If we use a line break in the second loop after passing 100 values or 50 values  it takes only 8 56 seconds and 7 05 seconds respectively    Random r   new Random    for  int i   0  i  lt  1000  i          for  int j   0  j  lt  1000  j              if r nextInt 4     0                System out print  O              else               System out print  B                      if j 100  0                   Adding a line break in second loop                   System out println                                            System out println                          Another advice is that to change settings of NetBeans IDE  First of all  go to NetBeans Tools and click Options  After that click Editor and go to Formatting tab  Then select Anywhere in Line Wrap Option  It will take almost 6 24  less time to compile the program

[java] Why is printing "B" dramatically slower than printing "#"?

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