tomcat remote debug
1： ./catalina.sh jpda start
2: Configure in catalina.sh:
JPDA_TRANSPORT=dt_socket
JPDA_ADDRESS=5005
JPAD_SUSPEND=n
或者CATALINA_OPTS="-server -Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8899"
Java thread pool
Top-level interface: Executor
Tool class: Executors
Executor executor = Executors.newFixedThreadPool(3);
Difference and connection between stored procedure and stored function
Similarities: 1. The creation syntax is similar, and both can carry multiple incoming and outgoing parameters.
2. All are compiled once and executed multiple times.
Differences: 1. The stored procedure definition keyword uses procedure, and the function definition uses function.
2. The return value cannot be used in the stored procedure, but it can be used in the function, and there must be a return clause in the function.
3. The execution methods are slightly different. There are two execution methods of stored procedures (1. Use execute2. Use begin and end). In addition to the two methods of stored procedures, functions can also be used as expressions, such as in select (select f1() form dual;).
Summary: If there is only one return value, use a stored function, otherwise, generally use a stored procedure.