The Program Entrypoint

The entrypoint receives the instruction data byte slice and a slice of AccountInfo. Anchor's #[program] macro generates dispatch from the 8-byte discriminator to your handlers.

Recipe

use anchor_lang::prelude::*;
#[program]
pub mod my_program { /* handlers */ }

When to reach for this:

• Building or debugging on Agave 4.1.1
• Integrating with Anchor 0.32.1 programs
• Client work with @solana/kit 7.0.0

Working Example

// Native (without Anchor):
// entrypoint!(process_instruction);
// fn process_instruction(program_id, accounts, data) -> ProgramResult

What this demonstrates:

• Idiomatic patterns for the Agave 4.1 era
• Correct account and signer handling
• Observable behavior via logs or RPC

Deep Dive

How It Works

• Solana programs execute in the Sealevel parallel runtime
• Transactions declare all accounts; non-overlapping work runs in parallel
• Compute is metered in CUs; rent-exempt accounts persist state

Gotchas

• Stale web3.js v1 examples - use @solana/kit 7.0.0. Fix: migrate client code.
• Missing signer flags - txs fail at runtime. Fix: mark signers explicitly.
• Expired blockhash on retry - silent drops. Fix: refresh and re-sign.
• Wrong cluster RPC - accounts not found. Fix: match cluster end-to-end.
• Undersized account space - init fails. Fix: use InitSpace in Anchor 0.32.1.

Alternatives

FAQs

Related

• Programs Basics
• The SVM & sBPF

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.