Workflow Execution Guide
Comprehensive guide to workflow execution in Axon OS, covering execution engines, runtime behavior, monitoring, and optimization.
Execution Overview
Axon OS provides a robust workflow execution engine that handles complex automation scenarios with high reliability, scalability, and performance.
Key Features
- Multi-threaded Execution: Parallel node processing
- Resource Management: CPU, memory, and I/O optimization
- Fault Tolerance: Automatic retries and error recovery
- State Management: Persistent execution state
- Real-time Monitoring: Live execution tracking
- Scalable Architecture: Horizontal scaling support
Execution Engine Architecture
Core Components
1. Workflow Scheduler
interface WorkflowScheduler {
schedule(workflow: WorkflowDefinition, trigger: TriggerEvent): Promise<ExecutionId>;
pause(executionId: ExecutionId): Promise<void>;
resume(executionId: ExecutionId): Promise<void>;
cancel(executionId: ExecutionId): Promise<void>;
getStatus(executionId: ExecutionId): Promise<ExecutionStatus>;
}
interface TriggerEvent {
type: 'manual' | 'scheduled' | 'webhook' | 'event';
payload: any;
metadata: TriggerMetadata;
}
interface TriggerMetadata {
userId: string;
timestamp: Date;
source: string;
priority: 'low' | 'normal' | 'high' | 'critical';
}
2. Execution Context
interface ExecutionContext {
executionId: string;
workflowId: string;
userId: string;
startTime: Date;
endTime?: Date;
status: ExecutionStatus;
variables: ExecutionVariables;
metadata: ExecutionMetadata;
resources: ResourceAllocation;
}
enum ExecutionStatus {
QUEUED = 'queued',
RUNNING = 'running',
PAUSED = 'paused',
COMPLETED = 'completed',
FAILED = 'failed',
CANCELLED = 'cancelled',
TIMEOUT = 'timeout'
}
interface ExecutionVariables {
input: any;
output?: any;
intermediate: Map<string, any>;
errors: ExecutionError[];
}
interface ResourceAllocation {
maxMemory: number;
maxCpu: number;
timeout: number;
priority: number;
}
3. Node Executor
interface NodeExecutor {
executeNode(
node: NodeDefinition,
input: NodeInput,
context: ExecutionContext
): Promise<NodeOutput>;
validateNode(node: NodeDefinition): ValidationResult;
getNodeMetrics(nodeId: string): NodeMetrics;
}
interface NodeInput {
data: any;
metadata: InputMetadata;
context: ExecutionContext;
}
interface NodeOutput {
data: any;
metadata: OutputMetadata;
success: boolean;
error?: NodeError;
metrics: NodeExecutionMetrics;
}
interface NodeExecutionMetrics {
startTime: Date;
endTime: Date;
duration: number;
memoryUsed: number;
cpuUsed: number;
ioOperations: number;
}
Execution Modes
1. Sequential Execution
Default execution mode where nodes execute in order:
class SequentialExecutor implements WorkflowExecutor {
async execute(workflow: WorkflowDefinition, context: ExecutionContext): Promise<ExecutionResult> {
const nodeOrder = this.topologicalSort(workflow.nodes);
const results: Map<string, NodeOutput> = new Map();
for (const nodeId of nodeOrder) {
const node = workflow.nodes.find(n => n.id === nodeId);
if (!node) continue;
try {
// Prepare input from previous nodes
const input = this.prepareNodeInput(node, results, context);
// Execute node
const output = await this.nodeExecutor.executeNode(node, input, context);
results.set(nodeId, output);
// Update execution context
context.variables.intermediate.set(nodeId, output.data);
if (!output.success) {
throw new NodeExecutionError(node.id, output.error);
}
} catch (error) {
return this.handleExecutionError(error, context);
}
}
return {
success: true,
output: this.collectFinalOutput(results),
metrics: this.calculateMetrics(results)
};
}
}
2. Parallel Execution
Concurrent execution of independent nodes:
class ParallelExecutor implements WorkflowExecutor {
private maxConcurrency: number = 10;
private semaphore: Semaphore;
constructor(maxConcurrency?: number) {
this.maxConcurrency = maxConcurrency || 10;
this.semaphore = new Semaphore(this.maxConcurrency);
}
async execute(workflow: WorkflowDefinition, context: ExecutionContext): Promise<ExecutionResult> {
const dependencyGraph = this.buildDependencyGraph(workflow);
const executionLevels = this.calculateExecutionLevels(dependencyGraph);
const results: Map<string, NodeOutput> = new Map();
for (const level of executionLevels) {
// Execute all nodes in current level in parallel
const levelPromises = level.map(nodeId =>
this.executeNodeWithSemaphore(nodeId, workflow, results, context)
);
const levelResults = await Promise.allSettled(levelPromises);
// Check for failures
const failures = levelResults
.filter((result): result is PromiseRejectedResult => result.status === 'rejected')
.map(result => result.reason);
if (failures.length > 0) {
return this.handleParallelFailures(failures, context);
}
}
return {
success: true,
output: this.collectFinalOutput(results),
metrics: this.calculateMetrics(results)
};
}
private async executeNodeWithSemaphore(
nodeId: string,
workflow: WorkflowDefinition,
results: Map<string, NodeOutput>,
context: ExecutionContext
): Promise<void> {
await this.semaphore.acquire();
try {
const node = workflow.nodes.find(n => n.id === nodeId);
if (!node) return;
const input = this.prepareNodeInput(node, results, context);
const output = await this.nodeExecutor.executeNode(node, input, context);
results.set(nodeId, output);
context.variables.intermediate.set(nodeId, output.data);
if (!output.success) {
throw new NodeExecutionError(node.id, output.error);
}
} finally {
this.semaphore.release();
}
}
}
3. Event-Driven Execution
Reactive execution based on events and conditions:
class EventDrivenExecutor implements WorkflowExecutor {
private eventBus: EventBus;
private conditionEvaluator: ConditionEvaluator;
async execute(workflow: WorkflowDefinition, context: ExecutionContext): Promise<ExecutionResult> {
// Set up event listeners for conditional nodes
this.setupEventListeners(workflow, context);
// Start with trigger nodes
const triggerNodes = workflow.nodes.filter(n => n.type === 'trigger');
for (const triggerNode of triggerNodes) {
this.eventBus.emit('node:ready', {
nodeId: triggerNode.id,
input: context.variables.input
});
}
// Wait for execution completion
return new Promise((resolve, reject) => {
const timeout = setTimeout(() => {
reject(new Error('Workflow execution timeout'));
}, context.resources.timeout);
this.eventBus.on('workflow:complete', (result) => {
clearTimeout(timeout);
resolve(result);
});
this.eventBus.on('workflow:error', (error) => {
clearTimeout(timeout);
reject(error);
});
});
}
private setupEventListeners(workflow: WorkflowDefinition, context: ExecutionContext): void {
this.eventBus.on('node:ready', async (event) => {
const node = workflow.nodes.find(n => n.id === event.nodeId);
if (!node) return;
// Check if all dependencies are satisfied
const dependenciesSatisfied = await this.checkDependencies(node, context);
if (!dependenciesSatisfied) return;
// Execute node
try {
const output = await this.nodeExecutor.executeNode(node, event.input, context);
// Emit completion event
this.eventBus.emit('node:complete', {
nodeId: node.id,
output: output
});
// Trigger dependent nodes
this.triggerDependentNodes(node, output, workflow);
} catch (error) {
this.eventBus.emit('node:error', {
nodeId: node.id,
error: error
});
}
});
}
}
State Management
Execution State Persistence
interface ExecutionState {
executionId: string;
workflowId: string;
status: ExecutionStatus;
currentNode?: string;
completedNodes: string[];
failedNodes: string[];
variables: ExecutionVariables;
checkpoints: Checkpoint[];
createdAt: Date;
updatedAt: Date;
}
interface Checkpoint {
id: string;
nodeId: string;
timestamp: Date;
state: any;
metadata: CheckpointMetadata;
}
class StateManager {
async saveState(state: ExecutionState): Promise<void> {
// Serialize state
const serializedState = this.serializeState(state);
// Store in database
await this.stateRepository.save(state.executionId, serializedState);
// Optionally store in Redis for quick access
if (state.status === ExecutionStatus.RUNNING) {
await this.redis.setex(
`execution:${state.executionId}`,
3600, // 1 hour TTL
JSON.stringify(serializedState)
);
}
}
async loadState(executionId: string): Promise<ExecutionState | null> {
// Try Redis first for active executions
const cachedState = await this.redis.get(`execution:${executionId}`);
if (cachedState) {
return this.deserializeState(JSON.parse(cachedState));
}
// Fallback to database
const persistedState = await this.stateRepository.load(executionId);
return persistedState ? this.deserializeState(persistedState) : null;
}
async createCheckpoint(executionId: string, nodeId: string, state: any): Promise<void> {
const checkpoint: Checkpoint = {
id: this.generateCheckpointId(),
nodeId,
timestamp: new Date(),
state: this.serializeCheckpointState(state),
metadata: {
size: JSON.stringify(state).length,
compression: 'gzip'
}
};
await this.checkpointRepository.save(executionId, checkpoint);
}
async restoreFromCheckpoint(executionId: string, checkpointId: string): Promise<ExecutionState> {
const checkpoint = await this.checkpointRepository.load(executionId, checkpointId);
if (!checkpoint) {
throw new Error(`Checkpoint ${checkpointId} not found`);
}
const state = await this.loadState(executionId);
if (!state) {
throw new Error(`Execution state ${executionId} not found`);
}
// Restore state to checkpoint
state.currentNode = checkpoint.nodeId;
state.variables.intermediate = this.deserializeCheckpointState(checkpoint.state);
state.status = ExecutionStatus.RUNNING;
return state;
}
}
Variable Scoping
interface VariableScope {
global: Map<string, any>; // Available throughout workflow
local: Map<string, any>; // Node-specific variables
input: Map<string, any>; // Input variables
output: Map<string, any>; // Output variables
}
class VariableManager {
private scopes: Map<string, VariableScope> = new Map();
setVariable(executionId: string, scope: string, name: string, value: any): void {
const variableScope = this.getOrCreateScope(executionId);
switch (scope) {
case 'global':
variableScope.global.set(name, value);
break;
case 'local':
variableScope.local.set(name, value);
break;
case 'input':
variableScope.input.set(name, value);
break;
case 'output':
variableScope.output.set(name, value);
break;
default:
throw new Error(`Invalid scope: ${scope}`);
}
}
getVariable(executionId: string, name: string): any {
const scope = this.scopes.get(executionId);
if (!scope) return undefined;
// Check scopes in order of precedence
return scope.local.get(name) ??
scope.global.get(name) ??
scope.input.get(name) ??
scope.output.get(name);
}
evaluateExpression(executionId: string, expression: string): any {
const scope = this.scopes.get(executionId);
if (!scope) throw new Error(`No scope found for execution ${executionId}`);
// Create evaluation context
const context = {
...Object.fromEntries(scope.global),
...Object.fromEntries(scope.local),
...Object.fromEntries(scope.input),
...Object.fromEntries(scope.output)
};
// Safe expression evaluation
return this.safeEvaluate(expression, context);
}
private safeEvaluate(expression: string, context: any): any {
// Use a safe evaluation method (e.g., expr-eval, vm2, or custom parser)
// This is a simplified example
try {
const func = new Function(...Object.keys(context), `return ${expression}`);
return func(...Object.values(context));
} catch (error) {
throw new Error(`Expression evaluation failed: ${error.message}`);
}
}
}
Resource Management
Resource Allocation
interface ResourceLimits {
maxMemory: number; // bytes
maxCpu: number; // CPU cores
maxExecutionTime: number; // milliseconds
maxFileSize: number; // bytes
maxNetworkRequests: number;
}
interface ResourceUsage {
currentMemory: number;
peakMemory: number;
cpuTime: number;
executionTime: number;
fileSystemWrites: number;
networkRequests: number;
}
class ResourceManager {
private resourcePools: Map<string, ResourcePool> = new Map();
private activeAllocations: Map<string, ResourceAllocation> = new Map();
async allocateResources(
executionId: string,
requirements: ResourceLimits
): Promise<ResourceAllocation> {
// Find appropriate resource pool
const pool = this.findBestPool(requirements);
if (!pool) {
throw new Error('No available resources for execution');
}
// Reserve resources
const allocation = await pool.allocate(requirements);
this.activeAllocations.set(executionId, allocation);
// Set up monitoring
this.startResourceMonitoring(executionId, allocation);
return allocation;
}
async releaseResources(executionId: string): Promise<void> {
const allocation = this.activeAllocations.get(executionId);
if (!allocation) return;
// Stop monitoring
this.stopResourceMonitoring(executionId);
// Release resources back to pool
await allocation.pool.release(allocation);
this.activeAllocations.delete(executionId);
}
private startResourceMonitoring(executionId: string, allocation: ResourceAllocation): void {
const monitor = setInterval(async () => {
const usage = await this.getCurrentUsage(executionId);
// Check for limit violations
if (usage.currentMemory > allocation.limits.maxMemory) {
this.handleResourceViolation(executionId, 'memory', usage.currentMemory);
}
if (usage.executionTime > allocation.limits.maxExecutionTime) {
this.handleResourceViolation(executionId, 'timeout', usage.executionTime);
}
// Update metrics
this.updateResourceMetrics(executionId, usage);
}, 1000); // Check every second
allocation.monitor = monitor;
}
private handleResourceViolation(
executionId: string,
violationType: string,
currentValue: number
): void {
console.warn(`Resource violation for ${executionId}: ${violationType} = ${currentValue}`);
// Emit warning event
this.eventBus.emit('resource:violation', {
executionId,
violationType,
currentValue
});
// Optionally terminate execution
if (violationType === 'memory' || violationType === 'timeout') {
this.terminateExecution(executionId, `Resource limit exceeded: ${violationType}`);
}
}
}
Memory Management
class MemoryManager {
private memoryPools: Map<string, MemoryPool> = new Map();
private gcThreshold: number = 0.8; // 80% memory usage
async allocateMemory(size: number, executionId: string): Promise<MemoryBlock> {
// Check if garbage collection is needed
const currentUsage = await this.getCurrentMemoryUsage();
if (currentUsage.ratio > this.gcThreshold) {
await this.runGarbageCollection();
}
// Allocate memory block
const pool = this.getOrCreatePool(executionId);
return pool.allocate(size);
}
async deallocateMemory(block: MemoryBlock): Promise<void> {
const pool = this.memoryPools.get(block.executionId);
if (pool) {
await pool.deallocate(block);
}
}
private async runGarbageCollection(): Promise<void> {
console.log('Running garbage collection...');
// Clean up completed executions
const completedExecutions = await this.getCompletedExecutions();
for (const executionId of completedExecutions) {
const pool = this.memoryPools.get(executionId);
if (pool) {
await pool.cleanup();
this.memoryPools.delete(executionId);
}
}
// Force Node.js garbage collection if available
if (global.gc) {
global.gc();
}
}
}
Error Handling and Recovery
Retry Mechanisms
interface RetryPolicy {
maxAttempts: number;
baseDelay: number; // milliseconds
maxDelay: number; // milliseconds
backoffFactor: number; // exponential backoff multiplier
jitter: boolean; // add random jitter
retryableErrors: string[]; // error types that should trigger retry
}
class RetryManager {
async executeWithRetry<T>(
operation: () => Promise<T>,
policy: RetryPolicy,
context: ExecutionContext
): Promise<T> {
let lastError: Error;
for (let attempt = 1; attempt <= policy.maxAttempts; attempt++) {
try {
return await operation();
} catch (error) {
lastError = error;
// Check if error is retryable
if (!this.isRetryableError(error, policy.retryableErrors)) {
throw error;
}
// Don't delay on last attempt
if (attempt < policy.maxAttempts) {
const delay = this.calculateDelay(attempt, policy);
await this.sleep(delay);
// Log retry attempt
console.log(`Retry attempt ${attempt + 1}/${policy.maxAttempts} after ${delay}ms`);
}
}
}
throw new Error(`Operation failed after ${policy.maxAttempts} attempts: ${lastError.message}`);
}
private calculateDelay(attempt: number, policy: RetryPolicy): number {
// Exponential backoff
let delay = Math.min(
policy.baseDelay * Math.pow(policy.backoffFactor, attempt - 1),
policy.maxDelay
);
// Add jitter to avoid thundering herd
if (policy.jitter) {
delay = delay * (0.5 + Math.random() * 0.5);
}
return Math.floor(delay);
}
private isRetryableError(error: Error, retryableErrors: string[]): boolean {
return retryableErrors.some(errorType =>
error.name === errorType ||
error.message.includes(errorType)
);
}
private sleep(ms: number): Promise<void> {
return new Promise(resolve => setTimeout(resolve, ms));
}
}
Circuit Breaker Pattern
enum CircuitState {
CLOSED = 'closed', // Normal operation
OPEN = 'open', // Failing fast
HALF_OPEN = 'half_open' // Testing recovery
}
interface CircuitBreakerConfig {
failureThreshold: number; // Number of failures to open circuit
recoveryTimeout: number; // Time to wait before testing recovery
successThreshold: number; // Successes needed to close circuit
timeout: number; // Operation timeout
}
class CircuitBreaker {
private state: CircuitState = CircuitState.CLOSED;
private failureCount: number = 0;
private successCount: number = 0;
private lastFailureTime: number = 0;
constructor(private config: CircuitBreakerConfig) {}
async execute<T>(operation: () => Promise<T>): Promise<T> {
if (this.state === CircuitState.OPEN) {
if (Date.now() - this.lastFailureTime < this.config.recoveryTimeout) {
throw new Error('Circuit breaker is OPEN');
} else {
this.state = CircuitState.HALF_OPEN;
this.successCount = 0;
}
}
try {
const result = await Promise.race([
operation(),
this.timeoutPromise()
]);
this.onSuccess();
return result;
} catch (error) {
this.onFailure();
throw error;
}
}
private onSuccess(): void {
this.failureCount = 0;
if (this.state === CircuitState.HALF_OPEN) {
this.successCount++;
if (this.successCount >= this.config.successThreshold) {
this.state = CircuitState.CLOSED;
}
}
}
private onFailure(): void {
this.failureCount++;
this.lastFailureTime = Date.now();
if (this.failureCount >= this.config.failureThreshold) {
this.state = CircuitState.OPEN;
}
}
private timeoutPromise(): Promise<never> {
return new Promise((_, reject) => {
setTimeout(() => {
reject(new Error('Operation timeout'));
}, this.config.timeout);
});
}
}
Performance Optimization
Execution Optimization
class ExecutionOptimizer {
optimizeWorkflow(workflow: WorkflowDefinition): OptimizedWorkflow {
const optimizations: Optimization[] = [];
// 1. Parallelize independent nodes
const parallelGroups = this.findParallelizableNodes(workflow);
if (parallelGroups.length > 0) {
optimizations.push({
type: 'parallelization',
description: `Found ${parallelGroups.length} groups of nodes that can run in parallel`,
impact: 'high',
groups: parallelGroups
});
}
// 2. Combine sequential operations
const combinableNodes = this.findCombinableNodes(workflow);
if (combinableNodes.length > 0) {
optimizations.push({
type: 'node_fusion',
description: `${combinableNodes.length} nodes can be combined to reduce overhead`,
impact: 'medium',
nodes: combinableNodes
});
}
// 3. Cache expensive operations
const cacheableNodes = this.findCacheableNodes(workflow);
if (cacheableNodes.length > 0) {
optimizations.push({
type: 'caching',
description: `${cacheableNodes.length} nodes benefit from caching`,
impact: 'medium',
nodes: cacheableNodes
});
}
// 4. Optimize data flow
const dataFlowOptimizations = this.optimizeDataFlow(workflow);
optimizations.push(...dataFlowOptimizations);
return {
originalWorkflow: workflow,
optimizedWorkflow: this.applyOptimizations(workflow, optimizations),
optimizations: optimizations,
estimatedSpeedup: this.calculateSpeedup(optimizations)
};
}
private findParallelizableNodes(workflow: WorkflowDefinition): ParallelGroup[] {
const dependencyGraph = this.buildDependencyGraph(workflow);
const groups: ParallelGroup[] = [];
// Find nodes with no dependencies between them
const visited = new Set<string>();
for (const node of workflow.nodes) {
if (visited.has(node.id)) continue;
const parallelNodes = this.findIndependentNodes(node.id, dependencyGraph, visited);
if (parallelNodes.length > 1) {
groups.push({
nodes: parallelNodes,
estimatedSpeedup: parallelNodes.length * 0.8 // Account for overhead
});
}
parallelNodes.forEach(nodeId => visited.add(nodeId));
}
return groups;
}
private optimizeDataFlow(workflow: WorkflowDefinition): Optimization[] {
const optimizations: Optimization[] = [];
// Find data transformation chains
const transformationChains = this.findTransformationChains(workflow);
for (const chain of transformationChains) {
if (chain.length > 2) {
optimizations.push({
type: 'transformation_fusion',
description: `Combine ${chain.length} data transformations into a single operation`,
impact: 'high',
nodes: chain
});
}
}
// Identify streaming opportunities
const streamingCandidates = this.findStreamingCandidates(workflow);
if (streamingCandidates.length > 0) {
optimizations.push({
type: 'streaming',
description: `Enable streaming for ${streamingCandidates.length} data-heavy operations`,
impact: 'high',
nodes: streamingCandidates
});
}
return optimizations;
}
}
Caching Strategy
interface CacheConfig {
enabled: boolean;
ttl: number; // Time to live in seconds
maxSize: number; // Maximum cache size in bytes
evictionPolicy: 'lru' | 'lfu' | 'ttl';
compression: boolean;
}
class ExecutionCache {
private cache: Map<string, CacheEntry> = new Map();
private config: CacheConfig;
constructor(config: CacheConfig) {
this.config = config;
this.startCleanupTimer();
}
async get(key: string): Promise<any | null> {
if (!this.config.enabled) return null;
const entry = this.cache.get(key);
if (!entry) return null;
// Check TTL
if (Date.now() > entry.expiresAt) {
this.cache.delete(key);
return null;
}
// Update access time for LRU
entry.accessedAt = Date.now();
entry.accessCount++;
return this.config.compression ?
this.decompress(entry.data) :
entry.data;
}
async set(key: string, value: any): Promise<void> {
if (!this.config.enabled) return;
const data = this.config.compression ?
this.compress(value) :
value;
const entry: CacheEntry = {
key,
data,
size: this.calculateSize(data),
createdAt: Date.now(),
accessedAt: Date.now(),
expiresAt: Date.now() + (this.config.ttl * 1000),
accessCount: 1
};
// Check size limits
while (this.getCurrentSize() + entry.size > this.config.maxSize) {
this.evictEntry();
}
this.cache.set(key, entry);
}
generateCacheKey(nodeId: string, input: any): string {
// Create deterministic cache key from node ID and input
const inputHash = this.hashObject(input);
return `${nodeId}:${inputHash}`;
}
private evictEntry(): void {
let entryToEvict: [string, CacheEntry] | null = null;
switch (this.config.evictionPolicy) {
case 'lru':
entryToEvict = Array.from(this.cache.entries())
.reduce((oldest, current) =>
current[1].accessedAt < oldest[1].accessedAt ? current : oldest
);
break;
case 'lfu':
entryToEvict = Array.from(this.cache.entries())
.reduce((leastUsed, current) =>
current[1].accessCount < leastUsed[1].accessCount ? current : leastUsed
);
break;
case 'ttl':
entryToEvict = Array.from(this.cache.entries())
.reduce((earliest, current) =>
current[1].expiresAt < earliest[1].expiresAt ? current : earliest
);
break;
}
if (entryToEvict) {
this.cache.delete(entryToEvict[0]);
}
}
}
Monitoring and Observability
Real-time Execution Monitoring
interface ExecutionMonitor {
startMonitoring(executionId: string): void;
stopMonitoring(executionId: string): void;
getMetrics(executionId: string): ExecutionMetrics;
getEvents(executionId: string): ExecutionEvent[];
}
interface ExecutionMetrics {
executionId: string;
status: ExecutionStatus;
startTime: Date;
endTime?: Date;
duration: number;
nodeMetrics: Map<string, NodeMetrics>;
resourceUsage: ResourceUsage;
throughput: number;
errorRate: number;
}
interface ExecutionEvent {
id: string;
executionId: string;
type: 'node:start' | 'node:complete' | 'node:error' | 'workflow:pause' | 'workflow:resume';
timestamp: Date;
nodeId?: string;
data: any;
}
class RealTimeMonitor implements ExecutionMonitor {
private activeMonitors: Map<string, NodeJS.Timer> = new Map();
private eventStore: Map<string, ExecutionEvent[]> = new Map();
startMonitoring(executionId: string): void {
const timer = setInterval(async () => {
const metrics = await this.collectMetrics(executionId);
// Emit metrics to real-time dashboard
this.eventBus.emit('execution:metrics', {
executionId,
metrics,
timestamp: new Date()
});
// Check for anomalies
const anomalies = this.detectAnomalies(metrics);
if (anomalies.length > 0) {
this.handleAnomalies(executionId, anomalies);
}
}, 1000); // Collect metrics every second
this.activeMonitors.set(executionId, timer);
}
stopMonitoring(executionId: string): void {
const timer = this.activeMonitors.get(executionId);
if (timer) {
clearInterval(timer);
this.activeMonitors.delete(executionId);
}
}
private detectAnomalies(metrics: ExecutionMetrics): Anomaly[] {
const anomalies: Anomaly[] = [];
// Check for memory leaks
const memoryGrowth = this.calculateMemoryGrowthRate(metrics.resourceUsage);
if (memoryGrowth > 0.1) { // 10% growth per minute
anomalies.push({
type: 'memory_leak',
severity: 'high',
description: `Memory usage growing at ${(memoryGrowth * 100).toFixed(1)}% per minute`
});
}
// Check for stuck nodes
for (const [nodeId, nodeMetrics] of metrics.nodeMetrics) {
if (nodeMetrics.status === 'running' && nodeMetrics.duration > 300000) { // 5 minutes
anomalies.push({
type: 'stuck_node',
severity: 'medium',
description: `Node ${nodeId} has been running for ${nodeMetrics.duration}ms`
});
}
}
return anomalies;
}
}
Scaling and Load Balancing
Horizontal Scaling
interface WorkerNode {
id: string;
host: string;
port: number;
capacity: ResourceCapacity;
currentLoad: ResourceUsage;
status: 'available' | 'busy' | 'offline';
lastHeartbeat: Date;
}
interface ResourceCapacity {
maxConcurrentExecutions: number;
maxMemory: number;
maxCpu: number;
}
class LoadBalancer {
private workerNodes: Map<string, WorkerNode> = new Map();
private roundRobinIndex: number = 0;
async scheduleExecution(
workflow: WorkflowDefinition,
requirements: ResourceLimits
): Promise<WorkerNode> {
// Find available workers that meet requirements
const availableWorkers = this.getAvailableWorkers(requirements);
if (availableWorkers.length === 0) {
throw new Error('No available workers for execution');
}
// Select worker based on load balancing strategy
const selectedWorker = this.selectWorker(availableWorkers);
// Reserve resources on selected worker
await this.reserveResources(selectedWorker, requirements);
return selectedWorker;
}
private getAvailableWorkers(requirements: ResourceLimits): WorkerNode[] {
return Array.from(this.workerNodes.values())
.filter(worker =>
worker.status === 'available' &&
this.hasCapacity(worker, requirements) &&
this.isHealthy(worker)
);
}
private selectWorker(workers: WorkerNode[]): WorkerNode {
// Use weighted round-robin based on current load
const weightedWorkers = workers.map(worker => ({
worker,
weight: this.calculateWeight(worker)
}));
// Sort by weight (higher is better)
weightedWorkers.sort((a, b) => b.weight - a.weight);
return weightedWorkers[0].worker;
}
private calculateWeight(worker: WorkerNode): number {
const memoryUtil = worker.currentLoad.currentMemory / worker.capacity.maxMemory;
const cpuUtil = worker.currentLoad.cpuTime / worker.capacity.maxCpu;
const executionUtil = worker.currentLoad.activeExecutions / worker.capacity.maxConcurrentExecutions;
// Lower utilization = higher weight
return 1 - Math.max(memoryUtil, cpuUtil, executionUtil);
}
}