同样的 ，多线程也存在许多缺点 ，在考虑多线程时需要进行充分的考虑。

多线程的主要缺点包括：Similarly, multi thread also has many shortcomings, in the consideration of the need for the full consideration of multiple threads. The main disadvantages of multi threading include:(1)等候使用共享资源时造成程序的运行速度变慢。

这些共享资源主要是独占性的资源 ，如打印机等。

(1) waiting for the use of shared resources, the running speed of the program is slow. These shared resources are exclusive resources, such as printers, etc..(2)对线程进行管理要求额外的 CPU开销。

线程的使用会给系统带来上下文切换的额外负担。

当这种负担超过一定程度时，多线程的特点主要表现在其缺点上，比如用独立的线程来更新数组内每个元素。

(2) an additional CPU overhead is required for the thread management. The use of threads will give the system the additional burden of context switching. When the load exceeds a certain level, the characteristics of multi thread are mainly expressed in its disadvantages, such as using independent thread to update each element in the array.(3)线程的死锁。

即较长时间的等待或资源竞争以及死锁等多线程症状。

(3) deadlock of thread. That is, waiting for a longer period of time to wait or resource competition and deadlock and other multi thread symptoms.(4)对公有变量的同时读或写。

当多个线程需要对公有变量进行写操作时，后一个线程往往会修改掉前一个线程存放的数据，从而使前一个线程的参数被修改；另外 ，当公用变量的读写操作是非原子性时，在不同的机器上，中断时间的不确定性，会导致数据在一个线程内的操作产生错误，从而产生莫名其妙的错误，而这种错误是程序员无法预知的(4) at the same time, read or write to the public variable. When multiple threads need to write operation to the public variable, a thread tend to modify off before a thread storage data, so that a thread parameters are modified; in addition, when public variable read and write operations are non atomic, on different machines, interrupt time of uncertainty, lead to the data in a thread operation generated errors, resulting in inexplicable error, and this error is unpredictable programmer