hadoop知識之counter

在mapper中

try  catch 異常中作如下處理：

context.getCounter("errorLines", "mapShortUrl").increment(1);

在界面中會看到如下的 計數。

	Counter	Map	Reduce	Total
errorLines	mapShortUrl	23,128	0	23,128
Job Counters	SLOTS_MILLIS_MAPS	0	0	23,779
	Launched reduce tasks	0	0	1
	Total time spent by all reduces waiting after reserving slots (ms)	0	0	0
	Rack-local map tasks	0	0	1
	Total time spent by all maps waiting after reserving slots (ms)	0	0	0
	Launched map tasks	0	0	1
	SLOTS_MILLIS_REDUCES	0	0	12,844