How to monitor the execution time and memory usage of Java sub-threads

How to get the execution time and memory usage of java sub-threads

There is no specific statement to check the memory size used by a thread in real time.

However, phased monitoring and analysis can be carried out through the before and after comparison method.

First add a static method:

public static long getmemory() {

return runtime.getruntime().freememory();

}

This is a statement to check the free memory at runtime.

So instrumentation should be performed before and after the thread execution point that needs to be detected.

long point1 = getmemory();

Thread call

long point2 = getmemory();

Note: In addition, there should be no other interference during this process (calling other threads or other operations)

You can even perform instrumentation in the thread, and then analyze the numerical changes of all points, and get the answer based on the numerical difference.

How to check mysql execution progress

Mysql system variables are divided into global variables and session variables. Modifications of global variables affect the entire server, and modifications of session variables only affect the current session.

Check whether the log is enabled

show variables like 'general_log'

set GLOBAL general_log='ON';

SET GLOBAL general_log_file = '/tmp/mysql.log'

Remember to turn it off when not in use, otherwise it will occupy a lot of disk space.

The show processlist command checks the sql statement currently being executed and can also check the user's current connection

View slow log

show variables like '%slow_query_log%';

show variables like 'long_query_time%'; set what kind of SQL the slow log records, the default is 10s

log-queries-not-using-indexes: Queries that do not use indexes are also recorded in the slow query log, and this variable is generally turned on

show status View mysql running status (to learn)

For example, check how many slow query records there are in mysql: show global status like '%Slow_queries%';

How android uses pid to determine whether the child process forked by the native code is running

1. Copy the application source code into the Android source code directory (compile the source code in advance)

2. Use build/envsteup.sh to configure shell -

mm TARGET_PRODUCT=product_name

Or directly ./build_android.sh can also complete the compilation.

3. There are three files in the source code directory: out/target/product/productname/obj/APPS/test_cert_intermediates: package.apk package.apk.unsigned package.apk.unaligned

Copy package.apk.unsigned and sign it separately

4. Sign under Windows: jarsigner -verbose -keystore youkey.keystore d:\package.apk.unsigned youkey

5.zipalign -v 4 d:\package.apk.unsigned d:\package.signed.apk

How nodejs detects the completion of child process execution

Nodejs is a single-threaded model, but multi-process tasks can be implemented using the child_process module of nodejs. Child_process can be used to create a child process and implement communication between the child process and the main process.

nodejs v0.12.7 version child_process provides the following synchronous and asynchronous ways to create processes:

Asynchronous creation:

child_process.spawn(command[, args][, options])

options.stdio

options.detached

options.customFds

child_process.exec(command[, options], callback)

child_process.execFile(file[, args][, options][callback])

child_process.fork(modulePath[, args][, options])

Synchronized creation:

child_process.spawnSync(command[, args][, options])

child_process.execFileSync(command[, args][, options])

child_process.execSync(command[, options])

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