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Make JBWAPI ready to connect as fast as possible - #97

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JavaBWAPI:developfrom
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@dgant

@dgant dgant commented Oct 28, 2026 •

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Most software stacks that run client bots (SC-Docker, Tournament Manager, SCHNAIL, for example) don't bother checking whether the client is connected before starting a game. There's not even an obviously good way to do this.

Instead they just launch the client bot, wait a few seconds, then launch StarCraft and pray the client is ready. This usually works, but when it doesn't, the bot fails to connect. The game is ruined.

This pull request aims to prevent failed connections by reducing the time required for client bots to be ready for connection. The measures include:

  • Don't allocate the asynchronous frame buffer until after connection.
  • Don't bind the whole Kernel32 interface, just the functions we need: OpenFileMapping and MapViewOfFile.
  • (Optional) Use pre-extracted JNA binaries. You can include them side-by-side with your bot JAR and save time on extracting them before connecting.

These changes were vibecoded but have undergone several rounds of iteration and testing. They reduce time-to-connection-ready by about 73%.

Defer frame buffers and metrics until after the BWAPI handshake, and use a focused Windows shared-memory mapping interface.

Automatically load an architecture-named JNA DLL beside the bot JAR after verifying it against the embedded binary. Preserve explicit JNA settings and ordinary loading when no matching bundle is available, without a custom native cache.

Package portable Windows DLLs beside the JAR and cover native loading, startup ordering, mapping behavior, and Windows Java 8 x86 in tests and CI.
client.reconnect();

// Allocate game bookkeeping and async frame buffers only after the BWAPI handshake.
this.performanceMetrics = new PerformanceMetrics(configuration);

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My naive assumption is that change is actually the most important for the startup boost (e.g. the Client starting to listen ASAP). Do you have individual timing on how much each of the 3 changes actually brings individually?


Client(BWClient bwClient) {
this.bwClient = bwClient;
JnaNativeLoader.initialize();

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nit: as we are checking the windowsOs one line below and this optimization is for windows anyways, perhaps we can transform this in a simple if else instead?

if (System.getProperty("os.name").toLowerCase().contains("win")) {
   JnaNativeLoader.initialize();
   clientConnector = new ClientConnectionW32();
} else {
   clientConnector = new ClientConnectionPosix();
}

/**
* Opens the BWAPI server's game table and game-state shared-memory mappings.
* Binding only these two kernel32 functions avoids initializing JNA's full
* Kernel32 proxy before the client can discover a server.

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Please add a small comment on how much time this is expected to save

SynchronizationEnvironment environment = new SynchronizationEnvironment(config);
environment.runGame(20);
final double minObserved = 0.25;
assertTrue("Copy to buffer: minimum must be positive",

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I copied your fix for broken head test in #101, thanks! Please rebase on top of develop head

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2 participants