深入理解Delphi内存管理器

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"本文主要探讨了Delphi编程中的内存管理机制,强调了内存管理的重要性以及在最小化内核中不包含内存管理器时可能导致的问题。Delphi提供了自己的内存管理器,包括默认的内存管理器和ShareMem.pas模块,后者用于在DLL与主机程序之间同步内存管理。虽然borlndmm.dll提供了内存管理功能,但其效率可能不高,因此开发者有时会选择第三方内存管理器以提升性能。在编写自定义内存管理器之前,需要深入理解Delphi的内存管理框架以避免潜在的问题。文章详细介绍了Delphi内存管理器的实现框架,包括通过操作系统API进行的内存分配(如VirtualAlloc和HeapAlloc)以及Delphi的堆分配,后者并不等同于操作系统的堆概念。Delphi的内存管理例程简化了内存分配的过程,使得开发者无需关注底层细节。" Delphi的内存管理器是其核心组件之一,尤其对于处理动态内存数据类型如AnsiString的应用程序至关重要。内存管理器负责内存的分配、使用和释放,以防止内存泄漏和提高程序效率。在最小化内核的环境中,没有内置的内存管理器,开发人员必须依赖Win32 API来手动管理内存,这可能导致效率低下并增加出错的风险。 Delphi提供了两种内存管理方案:默认的内存管理器和ShareMem.pas模块。ShareMem.pas与borlndmm.dll一起工作,确保DLL与宿主程序之间的内存管理一致性。然而,borlndmm.dll可能不是最高效的解决方案,开发者可能会寻找更优的第三方内存管理器来优化性能。 Delphi的内存管理器的实现主要在GetMem.inc文件中,它封装了操作系统API,允许程序员直接进行内存分配,而无需考虑具体的内存位置或管理细节。Delphi中的“堆分配”是指使用堆数据结构来管理内存,而不是指操作系统中的堆内存区域。这个堆数据结构使得内存分配更加灵活和高效。 为了有效地利用和控制内存,开发者需要理解Delphi内存管理器的工作原理,包括内存的分配方式(如虚拟地址内存分配和堆分配)以及如何通过操作系统API调用来实现这些分配。在尝试自定义内存管理器之前,深入学习这些基础知识至关重要,否则可能导致程序崩溃或其他不可预见的问题。因此,对内存管理的理解和掌握是Delphi开发中的关键技能。
2006-02-23 上传
Delphi 中少见的第三方内存管理器,QStrings 的作者 Andrew Driazgov 发布 QMemory is a new memory manager. You can use it as a replacement of the default system memory manager. To do this simply add QMemory unit in your project (as the first unit listed in the project file). Don‘t forget to call the QMemDecommitOverstock function when your application is idle. This subroutine decommits the unused memory blocks (it‘s only way for program to return the memory to the operation system). All allocated memory blocks are 32 byte aligned. The minimum size of the block is 32 bytes. As it is necessary to store some information with each block a dword is attached to the front of each block at -4 the aligned address. Thus, memory request for up to 28 bytes allocates a 32-bytes block, request for 29 to 60 bytes allocates a 64-bytes block, etc (as power of 2). This idea was adopted from HPMM project of Robert Lee (rhlee@optimalcode.com). The memory is committed and decommitted in 64K blocks. The maximum amount of the memory is specified when QMemInstall function is called (from the initialization section of the unit). You can‘t change this value later. If some parts of your program implemented as DLLs you have to use ShareQmm instead of QMemory unit. ShareQmm must be the first unit in your library‘s USES clause AND your project‘s (select Project-View Source) USES clause if some parts of your program have done as separate DLLs (especially if they export any procedures or functions that pass strings as parameters or function results). ShareQmm is the interface unit to the QMM.DLL shared memory manager, which must be deployed along with your DLL. You can‘t combine using of the standard ShareMem and custom ShareQmm memory managers in the same program project (including EXE-file with all DLLs). You can use either ShareMem or ShareQmm, but not both together. ShareQmm memory manager works at the same speed as a ShareMem memory manager with the blocks up to 4096 bytes and much more faster with the larger blocks.