Load Testing

The load package is a framework for performing load testing against an instance of the C-Chain. It allows for simulation of various transaction scenarios to test network performance, transaction throughput, and system resilience under different workloads.

This package also comes with main, a subpackage executable which runs a load test against an instance of the C-Chain. For information on how to run the executable, refer to the main README.md.

Prerequisites

Using the load package has so far been coupled with tmpnet, a framework that enables orchestration of temporary AvalancheGo networks. For more details as to its capabilities and configuration, refer to the tmpnet README.md.

Components

Worker

Workers represent accounts which will be used for load testing. Each worker consists of a private key, nonce, and a network client - these values are used to create a wallet for load testing.

Wallet

A wallet manages account state and transaction lifecycle for a single account.

The main function of wallets is to send transactions; wallets take signed transactions and send them to the network while monitoring block headers to detect transaction inclusion. A wallet considers a transaction successful if its execution succeeded, and returns an error otherwise. Upon confirming a transaction was successful, a wallet increments its nonce by one, ensuring its account state matches that of the network.

Wallets are not thread-safe and each account should have at most one wallet instance associated with it. Having multiple wallets associated with a single account, or using an account outside of a wallet, can cause synchronization issues. This risks a wallet's state becoming inconsistent with the network, potentially leading to failed transactions.

Wallets are not thread-safe and each account should have at most one wallet instance associated with it.

Generator

The generator executes multiple tests concurrently against the network. The key features of the generator are as follows:

• Parallel Execution: Runs a goroutine per wallet for concurrent test execution.
• Timeout Management: Supports both overall load test timeout and a timeout per-test.
• Error Recovery: Automatically recovers from test failures to ensure continuous load generation.
• Metrics: Creates metrics during wallet initialization and tracks performance throughout execution.

The generator starts a goroutine for each wallet to execute tests asynchronously, maximizing throughput while maintaining isolation between accounts.

Tests

The load package performs load testing by continuously running a series of tests. This approach provides the following benefits:

• Correctness: Each test validates transaction execution and state changes, ensuring the network behaves as expected under load
• Reproducibility: Standardized test scenarios with consistent parameters enable repeatable performance measurements and regression detection

Each test must satisfy the following interface for compatibility with the load generator:

type Test interface {
    // Run should create a signed transaction and broadcast it to the network via wallet.
    Run(tc tests.TestContext, wallet *Wallet)
}

Available Test Types

The load package provides a comprehensive suite of test types designed to stress different aspects of EVM execution. Each test targets specific performance characteristics and resource usage patterns.

Test Type	Description
Transfer	Performs self-transfer of 0 AVAX
Read	Performs multiple storage reads from contract state
Write	Executes equential storage writes to new contract storage slots
StateModification	Updates existing storage values or creates new ones
Hashing	Executes Keccak256 hash operations in a loop
PureCompute	Performs CPU-intensive mathematical computations
Memory	Allocates and manipulates dynamic arrays
CallDepth	Performs recursive function calls to test stack limits
ContractCreation	Deploys new contracts during execution
ExternalCall	Makes calls to external contract functions
LargeEvent	Emits events with large data payloads
TrieStress	Performs insert operations on TrieDB

Additionally, there is a RandomTest which executes one of the aforementioned tests, selected uniformly at random. This test is particular useful for mimicking the diverse transactions patterns seen on blockchains like the C-Chain.

Metrics

The package exposes Prometheus metrics for comprehensive load test monitoring:

• txs_issued (Counter): Total number of transactions submitted to the network
• tx_issuance_latency (Histogram): Time from transaction creation to network submission
• tx_confirmation_latency (Histogram): Time from network submission to block confirmation
• tx_total_latency (Histogram): End-to-end time from creation to confirmation

These metrics are registered with the registry passed into the load generator during initialization and are updated via the wallets during test execution.