Resize source

This page is part of the documentation for Orleans.Lattice 9.9.0 (release line 9.9), built 2026-10-04. It is also published as markdown, with every table and list, at source.md, and llms.txt lists every page.

The source of the Resize sample.

Program.cs

using System.Diagnostics;
using System.Text;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Orleans.Hosting;
using Orleans.Lattice;

// ---------------------------------------------------------------------------
// Resize - change a live tree's structural sizing with ResizeAsync.
//
// MaxLeafKeys / MaxInternalChildren control the tree's fan-out. They are pinned
// per tree in the registry, and the only supported way to change them on a tree
// that already holds data is ResizeAsync, which runs ONLINE: it drains the
// source into a freshly-sized destination tree (shadow-forwarding live writes)
// and atomically swaps the alias. Reads and writes stay available throughout and
// every entry is preserved verbatim. This sample populates a tree with 500
// entries (hashed across the default 64 shards, so each shard's root is still a
// single leaf), resizes it, and confirms the data survived.
// ---------------------------------------------------------------------------

using var host = Host.CreateDefaultBuilder(args)
    .ConfigureLogging(logging =>
    {
        logging.ClearProviders();
        logging.SetMinimumLevel(LogLevel.None);
    })
    .UseOrleans(silo =>
    {
        silo.UseLocalhostClustering();
        silo.AddMemoryGrainStorageAsDefault();
        silo.UseInMemoryReminderService();
        silo.AddLattice((s, name) => s.AddMemoryGrainStorage(name));
    })
    .Build();

await host.StartAsync();
var grainFactory = host.Services.GetRequiredService<IGrainFactory>();

Console.WriteLine("== Resize sample ==");
Console.WriteLine();

// Populate the tree with 500 entries - more than one leaf's default 128 keys, but
// hashed across the default 64 shards, so each shard's root stays a single leaf
// of about 8 keys. The resize still drains every entry into the freshly-sized
// destination tree.
const int count = 500;
var tree = grainFactory.GetGrain<ILattice>("catalog");
var entries = new List<KeyValuePair<string, byte[]>>(count);
for (var i = 0; i < count; i++)
    entries.Add(new KeyValuePair<string, byte[]>($"item:{i:D4}", Encoding.UTF8.GetBytes($"value-{i}")));
await tree.SetManyAsync(entries);

Console.WriteLine($"Populated 'catalog' with {await tree.CountAsync()} entries (default MaxLeafKeys=128).");
Console.WriteLine();

// Kick off the online resize to a wider leaf capacity. ResizeAsync returns once
// the pipeline is initiated; we poll IsResizeCompleteAsync until the alias swap
// and cleanup have finished.
Console.WriteLine("Calling ResizeAsync(newMaxLeafKeys: 256, newMaxInternalChildren: 64)...");
var sw = Stopwatch.StartNew();
await tree.ResizeAsync(newMaxLeafKeys: 256, newMaxInternalChildren: 64);

var deadline = TimeSpan.FromSeconds(60);
while (!await tree.IsResizeCompleteAsync())
{
    if (sw.Elapsed > deadline)
        throw new TimeoutException("Resize did not complete within the expected window.");
    await Task.Delay(200);
}
sw.Stop();
Console.WriteLine($"Resize completed in {sw.Elapsed.TotalSeconds:F1}s.");
Console.WriteLine();

// The tree ID is unchanged and every entry survived the re-paginate + swap.
Console.WriteLine($"CountAsync after resize -> {await tree.CountAsync()} (unchanged).");
var probe = await tree.GetAsync("item:0250");
Console.WriteLine($"item:0250 = {Encoding.UTF8.GetString(probe!)}");

// Writes keep working against the same logical tree after the swap.
await tree.SetAsync("item:new", Encoding.UTF8.GetBytes("post-resize"));
var newProbe = await tree.GetAsync("item:new");
Console.WriteLine($"item:new  = {Encoding.UTF8.GetString(newProbe!)} (written after the resize)");
Console.WriteLine("-> same tree, wider leaves, data intact and still writable.");

Console.WriteLine();
Console.WriteLine("Done.");
await host.StopAsync();

Resize.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <RootNamespace>Orleans.Lattice.Samples.Resize</RootNamespace>
    <AssemblyName>Orleans.Lattice.Samples.Resize</AssemblyName>
    <IsPackable>false</IsPackable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.11" />
    <PackageReference Include="Microsoft.Orleans.Server" Version="10.2.2" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\..\src\lattice\Orleans.Lattice.csproj" />
  </ItemGroup>

</Project>