Tuning Performance Bottlenecks

Though the execution of the function code is fast, using locks in multi-thread programming will cause lock contention, which is time-consuming. To reduce the preemption of public resources, you can tune the code by using atomic variable–based lock-free programming.

In this practice, pthread_atomic is the tuned application. Execute an analysis again to check whether the tuning takes effect.

1. Create a hotspot function analysis task again for the pthread_atomic application.

   Click next to the System Profiler and select General analysis. On the task creation page that is displayed, select Hotspot Function, set the required parameters, and click OK to start the hotspot function analysis task. Retain the default values for the parameters unless otherwise specified.

   If you create a hotspot function analysis task to monitor lock contention of your system, run the corresponding application demo in the backend when starting the task. Otherwise, lock contention data cannot be collected.

   Figure 1 Creating a hotspot function analysis task
   

   Table 1 Task parameters

   Parameter	Description
   Analysis Type	Set it to Hotspot functions.
   Analysis Object	Set it to Application.
   Application Path	/opt/testdemo/pthread_atomic
   Sampling Duration	Set it to 30.
   Sampling Frequency	100 times per second
   Sampling Range	Set it to User mode.
   dwarf	Enable this option.
   C/C++ Source File Directory	Associates the source code during collection. Example: /opt/testdemo/

2. View the analysis result.
   Figure 2 Hotspot function analysis result
   
3. Create a new lock and wait analysis task (pthread_atomic application).

   Click next to the System Profiler and select General analysis. On the task creation page that is displayed, select Locks and Waits, set the required parameters, and click OK to start the lock and wait analysis task. Retain the default values for the parameters unless otherwise specified.

   Figure 3 Creating a lock and wait analysis task
   

   Table 2 Task parameters

   Parameter	Description
   Analysis Type	Set it to Lock and wait analysis.
   Analysis Object	Set it to Application.
   Mode	Set it to Attach to process.
   PID	Select the process ID corresponding to the pthread_atomic application.
   Lock Analysis Type	Select all (select Histogram statistics and Lock variable analysis).
   Predefined Lock Type	Retain the default value.
   Sampling Duration	Set it to 60.
   Max. Collected Data	Set it to 1024.
   Stack Analysis	Set it to Disabled.

4. View the analysis result.
   Figure 4 Lock and Wait Information
   

   The analysis result shows that the number and total duration of lock instances have been greatly reduced.