windows上面修改最大使用端口数和time_await等待时间
注册表需要添加两个配置，位置：
HKEY_LOCAL_MACHINE SYSTEM CurrentControlSet Services Tcpip Parameters
MaxUserPort :65534
TcpTimedWaitDelay:30
然而这么配置了之后，压测一段时间任然会有connect use错误提示出现，怀疑是jmeter没有重用keep alive，官方配置发现有三个配置参数比较可疑：
# Idle connection timeout (Milliseconds) to apply if the server does not send
# Keep-Alive headers (default 0)
# Set this > 0 to compensate for servers that don't send a Keep-Alive header
# If <= 0, idle timeout will only apply if the server sends a Keep-Alive header
httpclient4.idletimeout=10000
# Check connections if the elapsed time (Milliseconds) since the last
# use of the connection exceed this value
httpclient4.validate_after_inactivity=0
# TTL (in Milliseconds) represents an absolute value.
# No matter what, the connection will not be re-used beyond its TTL.
httpclient4.time_to_live=0
这么调整了配置之后还是不靠谱，jmeter.properties，user.properties这两个文件都修改过，任然有错误出现。
最好在官方发现这么一段话：
Use KeepAlive
JMeter sets the Connection: keep-alive header. This does not work properly with the default HTTP implementation, as connection re-use is not under user-control. It does work with the Apache HttpComponents HttpClient implementations.
怀疑是jmeter使用的client的问题，把Http Request->Advanced里面的Client Implement选择为Java之后，问题解决，1000并发跑了好久都没有出错㋡