为什么我的服务器有很多的mysql线程？

我注意到我的服务器消耗了将近500 MB的RAM，并启动了19个线程，如下图所示。

MYSQL主题顶部图片：

这是configuration：

• MySQL服务器不启动
• Mysql由于一些奇怪的查询而崩溃
• 什么是MySQL服务器主机的最佳select？
• MySQL（mariadb）崩溃的问题
• 远程Mysql连接需要5秒钟build立

-------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.1.41-3ubuntu12 [OK] Operating on 32-bit architecture with less than 2GB RAM -------- Storage Engine Statistics ------------------------------------------- [--] Status: -Archive -BDB -Federated +InnoDB -ISAM -NDBCluster [--] Data in MyISAM tables: 136M (Tables: 256) [--] Data in InnoDB tables: 85M (Tables: 29) [--] Data in MEMORY tables: 126K (Tables: 1) [!!] Total fragmented tables: 70 -------- Performance Metrics ------------------------------------------------- [--] Up for: 8d 18h 35m 35s (8M q [11.203 qps], 509K conn, TX: 4B, RX: 934M) [--] Reads / Writes: 56% / 44% [--] Total buffers: 72.0M global + 2.8M per thread (100 max threads) [OK] Maximum possible memory usage: 347.8M (33% of installed RAM) [OK] Slow queries: 0% (74/8M) [OK] Highest usage of available connections: 16% (16/100) [OK] Key buffer size / total MyISAM indexes: 16.0M/58.1M [OK] Key buffer hit rate: 99.9% (317M cached / 259K reads) [OK] Query cache efficiency: 61.9% (3M cached / 4M selects) [!!] Query cache prunes per day: 60422 [OK] Sorts requiring temporary tables: 0% (5 temp sorts / 328K sorts) [!!] Joins performed without indexes: 18909 [OK] Temporary tables created on disk: 22% (32K on disk / 140K total) [OK] Thread cache hit rate: 99% (54 created / 509K connections) [!!] Table cache hit rate: 0% (64 open / 40K opened) [OK] Open file limit used: 10% (112/1K) [OK] Table locks acquired immediately: 99% (4M immediate / 4M locks) [!!] InnoDB data size / buffer pool: 86.0M/8.0M 

什么是错的，或者我可以如何减lessmysqld线程数？

服务器没有特别的stream量，这是一个虚拟主机托pipe两个网站低medstream量。