问题

时序数据库 IoTDB 1.3.3 版本 IoTDB 执行查询操作失败，日志打印提示 Too many open files。通过命令查看打开文件数，结果如下：

[root@0002 DataReceiver]# lsof|grep  28347|wc -l     DataNode
55444
[root@0002 DataReceiver]# lsof|grep  28207|wc -l    ConfigNode
18574

查看当前网络连接数，结果如下：

原因和解决方案

原因一：连接太多

解决方案：降一点客户端并发。

原因二：文件太多

解决方案：观察顺乱序文件数目以及各个模块文件的大小，TsFile 过多可以调优合并，顺序文件或者乱序文件过多可以修改配置。

 The priority of compaction execution
# INNER_CROSS: prioritize inner space compaction, reduce the number of files first
# CROSS_INNER: prioritize cross space compaction, eliminate the unsequence files first
# BALANCE: alternate two compaction types
# compaction_priority=BALANCE
# 优先执行空间内合并任务
compaction_priority=INNER_CROSS
# BALANCE 各种合并平等
# INNER_CROSS 优先进行顺序文件和顺序文件或乱序文件和乱序文件的合并
# CROSS_INNER 优先将乱序文件合并到顺序文件中

如果条件允许（系统资源利用率不高，对其他模块无影响的情况下），可以适当再调大合并写入限速、合并任务并发数，加速合并。

How many threads will be set up to perform compaction, 10 by default.
# Set to 1 when less than or equal to 0.
# Datatype: int
# compaction_thread_count=1# The limit of write throughput merge can reach per second
# values less than or equal to 0 means no limit
# Datatype: int, Unit: megabyte
# compaction_write_throughput_mb_per_sec=16
# 每秒可达到的写入吞吐量合并限制。# The number of sub compaction threads to be set up to perform compaction.
# Currently only works for nonAligned data in cross space compaction and unseq inner space compaction.
# Set to 1 when less than or equal to 0.
# Datatype: int
# sub_compaction_thread_count=4
# 每个合并任务的子任务线程数，只对跨空间合并和乱序空间内合并生效