2013-07-24

Tempering Garbage Collection

I'm currently fighting against out of memory errors on an heavy-loaded Java server.

If only it had been implemented in Delphi and mORMot!
But at this time, the mORMot was still in its burrow. :)
Copy-On-Write and a good heap manager can do wonders of stability.

Here are some thoughts about Garbage Collector, and how to temper their limitations.
They may apply to both the JVM and the .Net runtime, by the way.

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2013-05-11

Delphi XE4 NextGen compiler: using byte instead of ansichar?

When I first read the technical white paper covering all of the language changes in XE4 for mobile development (tied to the new ARM LLVM-based Delphi compiler), I have to confess I was pretty much confused.

Two great mORMot users just asked for XE4/iOS support of mORMot.

Win32/Win64 support for XE4 will be done as soon as we got a copy of it.
I suspect the code already works, since it was working as expected with XE3, and we rely on our own set of low-level functions for most internal work.

But iOS-targetting is more complex, due to the NextGen compiler, mainly.

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2013-03-26

Delphi is just a perfect fit for the average programmer

On the Embarcadero forums, some user did have a perfectly sane reaction, about a non obvious integer type cast like Int64Var := Int32Var*Int32Var, which may overflow.

We've got to stop becoming, as one poster put it, "human pre-compilers" for Delphi.
The compiler ought to have the common sense to not need the programmer to cast the two integer values.

I respectfully think just the opposite.
;)

Such a type cast is part of the language grammar.
If you know the grammar, you will know how it will be compiled.

To be honest, you have the same in all languages, with more or less range checking, optimization, and implicit conversion.
This is why I like Delphi: it can be mastered by any programmers, whereas truly mastering Java or .Net needs a genius.


Delphi is just... human...

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2013-03-23

Download latest version of sqlite3.dll for Windows 64 bit

Update: We now build the amalgamation file with mingw and release the latest version of SQLite3, from this direct SQLite3-64.7z link, as soon as it is published on the SQLite3 site. Up to now, there is no official Win64 version of the SQlite3 library released in http://sqlite.org.. It is in fact  […]

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2013-02-25

Using external MinGW/VisualC++ sqlite3.dll - including benchmark

With upcoming revision 1.18 of the framework, our SynSQlite3.pas unit is able to access the SQLite3 engine in two ways:

  • Either statically linked within the project executable;
  • Or from an external sqlite3.dll library file.

The SQLite3 APIs and constants are defined in SynSQlite3.pas, and accessible via a TSQLite3Library class definition. It defines a global sqlite3 variable as such:

var
  sqlite3: TSQLite3Library;

To use the SQLite3 engine, an instance of TSQLite3Library class shall be assigned to this global variable. Then all mORMot's calls will be made through it, calling e.g. sqlite3.open() instead of sqlite3_open().

There are two implementation classes:

Class Unit Purpose
TSQLite3LibraryStatic SynSQLite3Static.pas Statically linked engine (.obj within the .exe)
TSQLite3LibraryDynamic SynSQLite3.pas Instantiate an external sqlite3.dll instance

Referring to SynSQLite3Static.pas in the uses clause of your project is enough to link the .obj engine into your executable.

Warning - breaking change: before version 1.18 of the framework, link of static .obj was forced - so you must add a reference to SynSQLite3Static in your project uses clause to work as expected.

In order to use an external sqlite3.dll library, you have to set the global sqlite3 variable as such:

 FreeAndNil(sqlite3); // release any previous instance (e.g. static)
 sqlite3 := TSQLite3LibraryDynamic.Create;

Of course, FreeAndNil(sqlite3) is not mandatory, and should be necessary only to avoid any memory leak if another SQLite3 engine instance was allocated (may be the case if SynSQLite3Static is referred somewhere in your project's units).

Here are some benchmarks, compiled with Delphi XE3, run in a 32 bit project, using either the static bcc-compiled engine, or an external sqlite3.dll, compiled via MinGW or Microsoft Visual C++.

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2012-11-13

Go language and Delphi

Do you know the Go language?

It is a strong-typed, compiled, cross-platform, and concurrent.
It features some nice high-level structures, like maps and strings, and still have very low-level access to the generated code: pointers are there, in a safe strong-typed implementation just like in pascal, and there is even a "goto", which sounds like an heresy to dogmatic coders, but does make sense to me, at least when you want to optimize code speed, in some rare cases.

It is created/pushed by Google, used internally by the company in their computer farms, and was designed by one of the original C creators.

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