今天将消费者线程数提高测试了一下，发现一个奇怪的错误。
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ProductDetailDataHandler, [queueSize=1000] exit, current working consumer thread count is: 15Exception in thread "Handler_12" java.lang.NoClassDefFoundError: com/alibaba/intl/app/datamigration/productdetail/util/ProductDetailSerializeObjectConverter
at com.alibaba.intl.app.datamigration.productdetail.ProductDetailDataHandler.insertRecordToDestDB(ProductDetailDataHandler.java:106)
at com.alibaba.intl.app.datamigration.productdetail.ProductDetailDataHandler.handleData(ProductDetailDataHandler.java:79)
at com.alibaba.intl.app.datamigration.productdetail.ProductDetailDataHandler.handleData(ProductDetailDataHandler.java:63)
at com.alibaba.intl.app.datamigration.DataHandler.run(DataHandler.java:77)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.ClassNotFoundException: com.alibaba.intl.app.datamigration.productdetail.util.ProductDetailSerializeObjectConverter
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 5 more
Caused by: java.io.FileNotFoundException: /home/forrest/work/data-migration/target/classes/com/alibaba/intl/app/datamigration/productdetail/util/ProductDetailSerializeObjectConverter.class (Too many open files)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:106)
at sun.misc.URLClassPath$FileLoader$1.getInputStream(URLClassPath.java:1001)
at sun.misc.Resource.cachedInputStream(Resource.java:59)
at sun.misc.Resource.getByteBuffer(Resource.java:154)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:249)
at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
... 11 more
报Too many open files，这是因为每个连接其实就是一个文件描述符，所以连接数太多会导致无法打开新文件。默认是1024个openfile。我启动了8个线程。每个线程有128个连接，所有线程共享一个打开文件描述符数组。所以就爆满了。