The interface request takes too long. Jstack observes the lock holding

scene ： In the engineering A Middle note project B The interface completes some logic ,A Print a message for each interface called in the , It is observed that when the interface is called continuously for a period of time , It'll stick for a while , Then continue to execute . The boss gives advice to check jstack dump Stack information , View blocking and time-consuming operations .

1. At the command line terminal , Input jps View the current java process id;
   
2. jstack –l PID >>log.txt, PID Refers to the process Id, Output the stack information to... In the current directory log.txt In file .
   
   Explain the parameters ：
   -l long listings, Will print out additional lock information , It can be used in the lock of life and death jstack -l pid To observe lock holding
   -m mixed mode, Not only will it output Java Stack information , It will also output C/C++ Stack information （ such as Native Method ）
3. A detailed analysis of the stack , Reference resources jstack dump Detailed analysis of log files

Through the above analysis , A synchronizer was found in the log printing in the project , As a result, all interfaces are waiting for log printing ; Another problem is that authentication is too slow .

solve ：

1. Log level is set to error, Reduce the resources occupied by log printing ,p6spy Turn off to reduce resource consumption , Printing logs is very resource consuming , The synchronization in the log makes the interface in a waiting state .
2. tokenID Authentication uses local authentication , Or remove the certification , The original authentication using an Internet address , adopt Apache Access authentication interface ,Apache Default long connection , Will limit the number of connections , Waiting for connection release , Block the program .

besides , Setting that can increase the processing speed of the interface ：

1. Set up MySQL database ,my.ini

max_allowed_packet = 64M
innodb_buffer_pool_size =20G   -- You don't have to set it too large ,4096M It's OK 

2. Set the number of connections to the database , Increase the number of initial connections , maximum connection ：

# Define the initial number of connections   
initialSize=10  
# The maximum number of database connections for which the connection pool is active ,0 Means unrestricted , Indicates maximum concurrency 
maxActive=200 
# The maximum number of database connections for which the connection pool is idle , Take a non positive integer to indicate unrestricted , When this value is exceeded, redundant idle connections will be released 
maxIdle=20
# The minimum number of database connections for which the connection pool is idle , Below this value will create the missing connection , set up 0 unlimited   
minIdle=10
# When the connection pool runs out of connections , Waiting time for new requests （ That is, wait for other connections to be idle ）, Timeout return exception , millisecond   
maxWait=60000

3. modify Tomcat,server.xml

<Connector  
	executor="tomcatThreadPool"
	port="8280"  
	protocol="org.apache.coyote.http11.Http11Nio2Protocol" 
	enableLookups="false"  
	acceptCount="1500"               
	disableUploadTimeout="false"      
	connectionTimeout="180000" 		
	connectionUploadTimeout="300000"
	maxConnections="10000"              
	URIEncoding="UTF-8"                           
	redirectPort="8443"               
	compression="on"              
	compressionMinSize="1024" 
	useSendfile="false"
	keepAliveTimeout="60000"
	tcpNoDelay="true"
	noCompressionUserAgents="gozilla, traviata" 
	maxPostSize="-1"  
    maxParameterCount="-1"
   compressibleMimeType="text/html,text/xml,text/plain,text/css,text/javascript,application/javascript "   />

<Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
        maxThreads="150" minSpareThreads="4"/>

take tomcat Change the maximum number of connections in the thread pool to maxThreads=200;
http Long connection timeout keepAliveTimeout Set to keepAliveTimeout="2000"ms, Just call me , You don't need to keep a long connection to get data , Just release the useless connection quickly .