Delphi: How to organize source code to increase compiler performance?

Question

I\'m working on a large delphi 6 project with quite a lot of dependancies. It takes several minutes to compile the whole project. The recompilation after a few changes is so

Answer 1

The compiler will only compile units that have changed. If you have changed the code in the interface section all units that depend on the changed unit are compiled. If only code in the implementation section is changed, the compile will only that unit but presumably link all the modules. Implies a good design of interfaces up front but if you restructure the code to restrict changes to the implementation compile times might reduce. I have no idea by how much. This fact is mentioned in the Delphi help files under Multiple and indirect unit references in Delphi 7 "Using Delphi".

Answer 2

Try to install a ram disk and set your dcu output path to point there. This more than halved my compilation time with Delphi 2007 on top of DelphiSpeedUp.

Answer 3

Check are there any paths in search paths that aren't on your local machine.

i.e. Don't link to binaries on network shares, and check that the search path isn't checking any network shares.

Answer 4

Some things that could slow down the compiler

• Redundant units in your uses clause. See this question for a link to CnPack.
• Not explicitly adding units to your project file. You've already seem to have covered that.
• Changed compiler settings, most notably include TDD32 info.

Try to get rid of unused units in your uses clause and see if it makes a difference.

Answer 5

• U can automatically get rid of unnecesseary unit references, which is very efficient optimization for compiling speed.

• In your situation, dividing your project into packages can improve compiling speed. With this way, it just generates modified package(s), not single massive binary for each recompilation. Working with packages can also help about easy deployment of your project updates.

• Turn off your live scanning antivirus

Answer 6

A few years later I am struggling again with increasing compiling times. I am currently using Delphi XE4 and I am at a point where I absolutely need to refactor the units references. I thought about a new way to identify where are the problems:

I’m using Process Monitor from Microsoft/SysInternals to monitor the compiler:

1. I start Process Monitor with a filter to show only dcc32.exe (or bds.exe when working from the IDE).
2. I build my project from the command line.
3. At the end I look at the CreateFile operations in the log of Process Monitor.

For each unit there will an entry for the .PAS file (when the compiler starts working on this unit) and one for the .DCU file (when the compiler is complexly done with this unit). By working on the log with a text editor and/or with Excel I can extract this kind of information:

• A kind of “tree”, where you recursively see in which order the units have been compiled.
• For each unit the delay between “.PAS file opened“ and “.DCU file written”.

Then I try to interpret the results to find places where doing some refactoring would speed the compile time. It is not so easy, but I’m getting some encouraging results.