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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for February 20th, 2020

Delphi memory allocators and configuration notes in multi-threaded environments with high allocation/deallocation rates

Posted by jpluimers on 2020/02/20

From an interesting discussion at [] FaceBook: Delphi developer thread by Jarto Tarpio with some measurements by Jarto Tarpio and André Mussche.

  • Manipulation of strings and lists in Delphi have high memory allocation/deallocation rates, so HTTP related services with high call rates are affected more than regular services
  •  FastMM:
    • conditional defines that can help are NeverSleepOnThreadContention, UseSwitchToThread, and UseReleaseStack then measure.
    • has one huge advantage: It’s very, very good at keeping memory fragmentation at bay
    • default settings are for applications that use lots of CPU, but have no really high memory allocation/deallocation rates
    • has very good debugging facilities
    • Under FullDebugMode address space is never released back to the operating system so once the address space has been exhausted there is very little room to manoeuvre.
  • TCMalloc:
    • is very good at multi-threaded memory management with high allocation/deallocation rates
    • needs to be persuaded to releases memory to the OS:
      it only releases to the system under two occasions: Freeing another part of the memory, or asking it to release all parts marked as freed.

    • has no debugging facilities

The differences make it a challenge to integrate in your development and deployment process: because of the debugging facilities, you’d like FastMM in all your environments, but TCMalloc in multi-threaded environments with high allocation/deallocation rates.

One possibility is to have your CI environment deliver both in all stages, run all tests on both, then choose the final one depending on your run-time configuration.

That gives a burden on configuring your Continuous Integration, but the gain might outweigh this cost.

Relevant links from the Facebook thread:


Posted in Delphi, Development, FastMM, Software Development | 5 Comments »

More great free Python books

Posted by jpluimers on 2020/02/20

A while ago I wrote about Until 20171201 you can get free access to “Automate the Boring Stuff with Python”?.

That book is still free. And these great books are too:

Via: [WayBack] Cracking Codes with Python by @AlSweigart teaches complete beginners how to program in Python. The book features the source code to several ciphers and … – ThisIsWhyICode – Google+


Posted in Development, Python, Scripting, Software Development | Leave a Comment »

Writing a Time Series Database from Scratch | Fabian Reinartz

Posted by jpluimers on 2020/02/20

Long read but very much worth it: [WayBack] Writing a Time Series Database from Scratch | Fabian Reinartz.

On using the file systems strengths for a flexible time series database that is both fast to write, and read millions of data points per second.


Similarly interesting: [WayBack] Translations: This article was translated to Simplified Chinese by Xiong Duo and to Korean by Matt Lee (이 성욱). Introduction I want to make solid-state


Posted in Development, Power User, Software Development, Systems Architecture | Leave a Comment »

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