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dreignier / cg-brutaltester

A local arena for codingame multiplayer puzzles
GNU General Public License v3.0
208 stars 45 forks source link

Small changes to avoid input exeptions and to have better log #4

Closed jfbogusz closed 7 years ago

jfbogusz commented 7 years ago

1) Changing Scanner to BufferedReader solved my problem with exeptions when waiting for player input. 2) Moving one line of logging to loop and adding logging player's stderr stream just after reading player's input give me log more readable and complete

dreignier commented 7 years ago

What was the problem with the Scanner ?

jfbogusz commented 7 years ago

When I used Scanner I received sometimes (1 on 6-10 games) following error: 22:54:49,996 ERROR [com.magusgeek.brutaltester.GameThread] Exception in game 1 java.util.NoSuchElementException: No line found at java.util.Scanner.nextLine(Scanner.java:1540) ~[?:1.8.0_121] at com.magusgeek.brutaltester.GameThread.run(GameThread.java:113) [cg-brutaltester-0.0.1-SNAPSHOT.jar:?]

When I changed to BufferedReader - I never received such error again (in more then 600 games). So I do not understund why it helps - but it solved my problam. You do not have such Exceptions?

dreignier commented 7 years ago

I don't have the problem. Using a BufferedReader can cause some weird behavior when an AI crash. A scanner will throw a NoSuchElementException when the process is dead (AI has crashsed). A BufferedReader will just wait indefinitely.

It's a little weird that you have this exceptions with a Scanner.

jfbogusz commented 7 years ago

Maybe Scanner has timer for waiting and it is some kind of timeout? My AI is not very fast (around 40 ms from input to output) but do not crash. So I will check it once again today evening. :-)

dreignier commented 7 years ago

Scanner has no timeout. If a scanner throw a NoSuchElementException, it is because the stream is closed (mostly because the AI process crashed) or because the stream is not opened when the scanner try to read it. I think you are in the second case. Your AI is maybe too slow to start so the scanner is plugged on a non existent stream. It is a interesting case and it would be useful to fix this bug.

What language and commandline do you use to start your AI ?

jfbogusz commented 7 years ago

My AI is written in C++. I use simple bash command on Ubuntu. Problem is not on begining (starting of the AI) - it is in midle of the game (for example after 10 - 20 turns). As I understund if it is problem with crash of my AI - BufferedReader will wait indefinitly - but it is not the case - BufferedReader reads as many lines as Referee need.

dreignier commented 7 years ago

How do you print your output in your AI ? Do you flush ? Codingame use a bash script to run our codes to perform an autoflush. But in real life, you have to flush.

jfbogusz commented 7 years ago

Maybe it is the problem. I do not flush. I will check it today evening. If so I will pull request with only changes in log. Thanks :-)

jfbogusz commented 7 years ago

It looks that problem is connected rather with my AI. So I close the pull.