FastMM5 Memory Manager

When memory allocated in one module (e.g., a DLL) is freed in another (e.g., the main application), you must ensure they share the same memory manager instance. Use the following functions:

• FastMM_ShareMemoryManager: Shares the memory manager instance of the current module with other modules.
• FastMM_AttemptToUseSharedMemoryManager: Switches the current module to use the memory manager of another module already in the process.

To use FastMM5, add FastMM5.pas as the first unit in your project's .DPR file. It will automatically install itself during application startup and replace the default Delphi memory manager.

If you need to control when FastMM is installed (rather than automatic startup installation), define FastMM_DisableAutomaticInstall in your conditional defines. In this case, you must manually call FastMM_Initialize very early in the unit initialization sequence (ideally in the first or second unit of your .DPR) and call FastMM_Finalize to uninstall it and perform leak checks.

// Standard automatic installationegin
program MyProject;
uses
  FastMM5, // Must be the first unit
  Forms, 
  Unit1 in 'Unit1.pas' if not debug;
begin
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

If you need to pin specific Delphi installation locations, use a file named CompilerPaths.txt placed in the same directory as the RunTests.ps1 script. This is useful for machines where the registry cannot be read or when you want to run tests against a specific set of versions.

Each line should contain one installation root. You can optionally provide a name using the format Name = Path. The name is used by the -Only flag in the PowerShell script. If no name is provided, the folder name is used.

Note: This file is ignored by .gitignore to prevent local configurations from being committed.

# One Delphi installation root per line, optionally "Name = Path".
# The name is what -Only matches; without one the folder name is used.
Athens  = C:\Program Files (x86)\Embarcadero\Studio\23.0
%ProgramFiles(x86)%\Embarcadero\Studio\22.0

The following optional units can be added to your project to gain deeper insights without affecting the core memory manager:

• FastMM_SamplingProfiler.pas: Runs a low-priority background thread that periodically samples memory state and writes time-series data to a CSV file. This is useful for tracking memory growth and fragmentation trends over time.
• FastMM_SnapshotDiff.pas: Captures point-in-time snapshots of live allocations and compares them. This helps identify which classes or data types are causing memory growth between two specific points in time.

FastMM5 allows you to route event notifications (like memory leaks or errors) to the debugger, a log file, the screen, or a combination.

Control routing via these variables:

• FastMM_LogToFileEvents: Route to a log file.
• FastMM_MessageBoxEvents: Route to a message box.
• FastMM_OutputDebugStringEvents: Route to the debugger via OutputDebugString.

To override the default log filename (which is based on the application path), use:

• FastMM_SetEventLogFilename

You can build and run an individual test program manually using dcc32. Ensure you compile from within the Tests directory so that older compilers can correctly resolve the in 'FastMM_TestUtils.pas' clause relative to the current directory.

dcc32 -B -U..;<lib\win32\release> -NSSystem;System.Win;Winapi;Vcl FastMM5Test_DebugMode.dpr
FastMM5Test_DebugMode.exe

Debug mode provides advanced features like detecting memory corruption and usage of freed objects (by filling freed blocks with the $808080... pattern). This comes at a performance and memory cost.

• FastMM_EnterDebugMode: Switches to debug mode ("FullDebugMode").
• FastMM_ExitDebugMode: Returns to performance mode.

Note: These calls can be nested. Debug mode remains active until the number of FastMM_ExitDebugMode calls matches the number of FastMM_EnterDebugMode calls.

FastMM_EnterDebugMode;
try
  // Perform memory intensive or risky operations
finally,
  FastMM_ExitDebugMode;
end;

You can adjust the balance between execution speed and memory efficiency at runtime using:

• FastMM_SetOptimizationStrategy: Sets the strategy to favor performance, low memory usage, or a blend of both (default).

If your application requires specific memory alignment (8, 16, 32, or 64 bytes) for all blocks, use the following functions:

• FastMM_EnterMinimumAddressAlignment: Requests a minimum block alignment.
• FastMM_ExitMinimumAddressAlignment: Rescinds the prior alignment request.

Note: Calls can be nested, and the coarsest (largest) alignment request currently in effect will take precedence.

FastMM_EnterMinimumAddressAlignment(32);
try
  // Code requiring 32-byte alignment
finally,
  FastMM_ExitMinimumAddressAlignment;
end;