lambda-performance-troubleshooting

name	lambda-performance-troubleshooting
description	AWS Lambda High Latency Troubleshooting

AWS Lambda High Latency Troubleshooting

Overview

This runbook helps diagnose and resolve AWS Lambda function performance issues including high latency, timeouts, and cold starts.

Steps

Step 1: Query Performance Metrics

Use CloudWatch to check Lambda function latency over time:

aws cloudwatch get-metric-statistics --namespace <lambda-namespace> \
  --metric-name Duration --dimensions Name=FunctionName,Value=<function-name> \
  --statistics Average,Maximum --start-time <start-time> \
  --end-time <end-time> --period 300

Step 2: Check Function Logs

Look for errors or slow operations in CloudWatch Logs:

aws logs filter-log-events --log-group-name <lambda-log-group>/<function-name> \
  --filter-pattern "[ERROR] OR [WARN] OR timeout" --limit 100

Step 3: Analyze Cold Start Patterns

Query CloudWatch for cold start frequency:

aws cloudwatch get-metric-statistics --namespace <lambda-namespace> \
  --metric-name InitDuration --dimensions Name=FunctionName,Value=<function-name> \
  --statistics Average,Count --start-time <start-time> \
  --end-time <end-time> --period 300

Step 4: Check Concurrent Executions

Verify Lambda isn't hitting concurrency limits:

aws cloudwatch get-metric-statistics --namespace <lambda-namespace> \
  --metric-name ConcurrentExecutions --dimensions Name=FunctionName,Value=<function-name> \
  --statistics Maximum --start-time <start-time> \
  --end-time <end-time> --period 60

Step 5: Review Memory Utilization

Check if function needs more memory allocation:

aws logs insights start-query --log-group-name <lambda-log-group>/<function-name> \
  --start-time <epoch-start> --end-time <epoch-end> \
  --query-string "fields @timestamp, @message | filter @type = 'REPORT' | stats max(@maxMemoryUsed), avg(@memorySize)"