07/15/16更新：它再次阻碍了......可能是因为我不小心删除了一些CleanMyMac，但我不知道我删除了什么。在过去的两天里，情况很好，所以必须是操作系统生成的东西。
07/13/16更新：在离开我的电脑两天后，这个问题已经不知何故消失了，但我仍然不确定为什么会这样。我发现我在tomcat中有一个死会话，不知道这是否相关。
原始问题：我正在做一些apache nutch开发，到上周五结束时，它一切顺利。但突然之间，我的程序今天运行速度非常慢，我在过去两天甚至没有触及我的工作文件，可能出现什么问题？
我尝试运行单节点hadoop示例，WordCount.java，apache hadoop wiki上提供的示例，输入文件只包含两个单词。在完成之前它跑了 2~3分钟。
日志文件相当简单，我找不到任何可以使用的东西。
2016-07-11 16:54:37,553 WARN util.NativeCodeLoader - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2016-07-11 16:56:38,174 WARN mapreduce.JobSubmitter - Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this.
2016-07-11 16:56:38,180 WARN mapreduce.JobSubmitter - No job jar file set. User classes may not be found. See Job or Job#setJar(String).
2016-07-11 16:56:38,445 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/staging/Nathaniel_Wu1492571083/.staging/job_local1492571083_0001/job.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.retry.interval; Ignoring.
2016-07-11 16:56:38,449 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/staging/Nathaniel_Wu1492571083/.staging/job_local1492571083_0001/job.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.attempts; Ignoring.
2016-07-11 16:56:38,608 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/local/localRunner/Nathaniel_Wu/job_local1492571083_0001/job_local1492571083_0001.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.retry.interval; Ignoring.
2016-07-11 16:56:38,611 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/local/localRunner/Nathaniel_Wu/job_local1492571083_0001/job_local1492571083_0001.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.attempts; Ignoring.
经过一段时间的研究，我发现如果我拔掉网络，它的运行速度可以非常快，总运行时间大约是 2~3秒。但是除了时间戳之外，日志几乎是一样的。
2016-07-11 17:01:30,536 WARN util.NativeCodeLoader - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
2016-07-11 17:01:30,928 WARN mapreduce.JobSubmitter - Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this.
2016-07-11 17:01:30,932 WARN mapreduce.JobSubmitter - No job jar file set. User classes may not be found. See Job or Job#setJar(String).
2016-07-11 17:01:31,192 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/staging/Nathaniel_Wu986778478/.staging/job_local986778478_0001/job.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.retry.interval; Ignoring.
2016-07-11 17:01:31,196 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/staging/Nathaniel_Wu986778478/.staging/job_local986778478_0001/job.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.attempts; Ignoring.
2016-07-11 17:01:31,340 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/local/localRunner/Nathaniel_Wu/job_local986778478_0001/job_local986778478_0001.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.retry.interval; Ignoring.
2016-07-11 17:01:31,342 WARN conf.Configuration - file:/tmp/hadoop-Nathaniel_Wu/mapred/local/localRunner/Nathaniel_Wu/job_local986778478_0001/job_local986778478_0001.xml:an attempt to override final parameter: mapreduce.job.end-notification.max.attempts; Ignoring.
我想这个问题与集群配置有关，但问题是，我根本没有配置，我的所有程序都应该是单节点的。我在Eclipse中运行我的程序，我只是导入了所需的类，并且根本没有编写任何配置文件。
现在我完全迷失了，我是hadoop的新手，请帮忙，这可能会导致这个问题？
顺便说一下，我在OS X上做了所有这些，这有关系吗？