Debugging Threads in Intel Parallel Studio

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Intel® Parallel Studio XE

Intel Parallel Studio XE is a software development tool suite for compiling applications and optimizing performance with less effort.

The Intel C++ Compiler is not the only tool that comes with IPS XE 2019. It also includes next applications:

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Intel® Advisor
Intel® Inspector
Intel® VTune™ Amplifier

Let's take a quick look at each of them:

Intel® Advisor

Vectorization optimization and thread prototyping.

Use this tool in the vectorization and threading stages of the flow.

Identify where it is safe to force compiler vectorization.
Quickly find what's blocking vectorization capabilities.
Use Threading Advisor to fast-track threading design.
Delivers the data and tips you need to make faster design and optimization decisions.

Intel® Inspector

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Memory and thread debugger.

Use this tool to find races, deadlocks, and illegal memory accesses.

Locate root cause errors early―before you release
Quickly debug intermittent races and deadlocks

Intel® VTune™ Amplifier

Performance profiler.

Use this tool in the threading and bandwidth optimization stages and for advanced vectorization optimization.

Save money: Locate root cause errors early―before you release
Save time: Quickly debug intermittent races and deadlocks

Intel Inspector

Intel Inspector is a dynamic memory and threading error checking instrument to inspect serial and multi-threaded programs.

Intel Inspector comes with Intel Parallel Studio XE along with two other debugging tools - VTune and Advisor.

Create a project

There are 2 ways to work with inspector.

Run inspector directly from Visual Studio

This is the easiest and fastest way that requires no additional configurations.

Run as a separate program.

Working with Intel Inspector application requires passing it a compiled version of your program. Additionally you may need to link some libraries (lib, dll, etc).

Configure a project

Intel suggests using small data set sizes and load threads with small chunks of work..

This will reduce run time and the speed of the analysis.

Choose analysis type

Inspector allows you to choose between predefined types of analysis.

Choose the type of Analysis using a drop-down menu (2):

Memory error analysis
- Detect leaks
- Detect Memory problems
- Locate memory problems

Threading error analysis
- Detect deadlocks
- Detect deadlocks and data races
- Locate deadlocks and data races

Custom analysis types - users can create their own types based on selected preset type.

Use a slider (3) to select a predefined analysis type.

Types at the the top have smaller a scope but faster in execution;

Types at the the bottom have larger a scope but they are considerably slower;

Edit settings of the analysis in the settings section (4)

How it works

Inspector performs the analysis in multiple steps:

1. The program is executed

2. It identifies problems that may need to be resolved.

3. Gathers problems.

4. Converts symbol information into filenames and line numbers.

5. Applies suppression rules.

6. Removes duplicates.

7. Creates problem sets.

8. Opens a debugging session.

Interpreting results

After the analysis completes, IPS XE Inspector will show you information on 2 pages:

Collection Log

Gives a general information about the execution of the program.

From there you can see the execution time, number of threads, the caller of threads, if they were active or not.

Summary

The Summary window is divided into 4 parts:

1) Problems section.

It shows problems (if any found) that we asked the Inspector to look for.

It provides you with a name of the problem, the file where the problem is located, the executable module which contains it, and the state of problem (which changes when do you a rescan).

2) Filters (On the right side of the Problems section)

Gives the summary of all problems (Source files affected, total of problems by type, etc)

3) Code locations

When we select a problem, code locations will show a preview of a source file and highlights the line on which the problems was detected!

Moreover it shows the operation that is performed (Read, Write), including thread operations.

Source files can be opened and edited directly from the Inspector by double clicking the problem.

4) Timeline

Shows threads that involved at the certain step.

Memory leak problem : https://www.codeproject.com/Tips/1184749/Allocating-Memory-in-C-Cplusplus-How-to-Avoid-Memo

Source

Shows source file and a call stack on different threads.

Intel VTune™ Amplifier

Introduction

Intel VTune amplifier is a analysis software that allows you the ability to measure performance of your serial or multithreaded program. VTune allows you to analyze the performance of your algorithms and multithreading. It can help with debugging threads by calculating overhead, finding bottlenecks or inefficiencies.