The first 1 1 Chapter common errors and solutions program
1 ) SecureCRT 7.3 garbled or can not delete data, install the free version of SecureCRT unloading or virtual machine installed directly manipulate or change version of SecureCRT
2 ) not connected mysql database
( 1 ) driver package in the wrong direction, should mysql-connector-java-5.1.27- bin.jar Import / opt / module / hive / lib not the packet. Mistake mysql-connector-java-5.1.27.tar.gz introduced hive / lib next packet.
( 2 ) modify the user host name of the table are not modified to % , but modified to localhost
3 ) Hive default input format processing is CombineHiveInputFormat , small files will be merged.
hive (default)> set hive.input.format;
hive.input.format=org.apache.hadoop.hive.ql.io.CombineHiveInputFormat
You may be employed HiveInputFormat will output file according to the number of partitions.
hive (default)> set hive.input.format=org.apache.hadoop.hive.ql.io.HiveInputFormat;
4 ) can not be executed mapreduce program
May be hadoop of yarn did not open.
5 ) Start mysql time service, newspaper MySQL server PID file could not be found ! Abnormality .
In / var / lock / subsys / mysql path down to create hadoop102.pid , and add content to the file: 4396
6) Daily service mysql status MySQL is not running, but lock file (/ var / lock / subsys / mysql [ failure ] ) abnormalities .
Solution: / var / lib / mysql create directory: . -Rw-rw ---- 1 MySQL MySQL 5 12 Yue 22 16:41 hadoop102.pid file, and modify the permissions to 777 .
7 ) the JVM heap memory overflow
描述：java.lang.OutOfMemoryError: Java heap space
Resolution: add the following code in the yarn-site.xml
<property> <name>yarn.scheduler.maximum-allocation-mb</name> <value>2048</value> </property> <property> <name>yarn.scheduler.minimum-allocation-mb</name> <value>2048</value> </property> <property> <name>yarn.nodemanager.vmem-pmem-ratio</name> <value>2.1</value> </property> <property> <name>mapred.child.java.opts</name> <value>-Xmx1024m</value> </property>