Fix clw-auth-oom: OpenClaw Authentication Out of Memory Error

1. Symptoms

The clw-auth-oom error indicates that the OpenClaw authentication service has exhausted available system memory during operation. This error manifests through several observable symptoms that system administrators should recognize:

Service-Level Symptoms:

The clw-auth service process terminates unexpectedly with exit code 137
Authentication requests begin failing with 401 Unauthorized responses
Previously authenticated sessions suddenly become invalid
The service fails to start on subsequent launch attempts

Application-Level Symptoms:

API clients receive Service Temporarily Unavailable responses during auth operations
Token validation operations hang indefinitely
New user login attempts timeout without response
Existing user sessions appear to be in a corrupted state

System-Level Symptoms:

Out-of-memory killer (oom-killer) log entries appear in system logs
Docker containers running clw-auth show status as Exited (137)
Kubernetes pods enter CrashLoopBackOff state
Memory usage graphs spike to 100% before service termination

# Typical error output in clw-auth logs
FATAL: clw-auth-oom: memory allocation failed
CRITICAL: service cannot allocate 8192 bytes for session cache
ERROR: authentication service terminated unexpectedly (exit code 137)

2. Root Cause

The clw-auth-oom error occurs when the OpenClaw authentication service attempts to allocate memory beyond what the operating system can provide. Understanding the root causes enables effective remediation:

Primary Cause: Unbounded Session Cache Growth The clw-auth service maintains an in-memory cache of authenticated sessions for performance optimization. When the session cache grows without limits, it eventually consumes all available memory. This commonly occurs when session cleanup routines fail to execute properly or when session expiration timestamps are misconfigured.

Secondary Cause: Memory Limit Misconfiguration Docker container or Kubernetes pod resource limits may be set below the actual memory requirements of the authentication service under production load. The default memory limits are often insufficient for high-throughput environments.

Tertiary Cause: Memory Leak in Session Handler Bugs in the session handling code can cause memory to be allocated but never released. Each authentication request incrementally consumes memory until the system exhausts available resources. Common leak patterns include:

Failed to remove session entries from cache after expiration
Circular references preventing garbage collection
Unclosed database connections accumulating in memory
Large token payload data being duplicated during caching

Contributing Factor: Insufficient Swap Configuration Systems without adequate swap space cannot gracefully handle memory pressure. When physical RAM is exhausted, the service is immediately terminated rather than being swapped to disk.

3. Step-by-Step Fix

Step 1: Increase Container Memory Limits (Docker)

If running OpenClaw in Docker containers, modify the memory allocation to provide adequate resources:

Before:

# docker-compose.yml
services:
  clw-auth:
    image: openclaw/auth-service:latest
    container_name: clw-auth
    ports:
      - "8443:8443"
    # Memory limit not explicitly set - relies on defaults
    environment:
      - CLAW_AUTH_PORT=8443
      - CLAW_SESSION_CACHE=enabled

After:

# docker-compose.yml
services:
  clw-auth:
    image: openclaw/auth-service:latest
    container_name: clw-auth
    ports:
      - "8443:8443"
    deploy:
      resources:
        limits:
          memory: 2048M
        reservations:
          memory: 1024M
    environment:
      - CLAW_AUTH_PORT=8443
      - CLAW_SESSION_CACHE=enabled
      - CLAW_SESSION_MAX_AGE=3600
      - CLAW_SESSION_CACHE_MAX_SIZE=10000
    mem_limit: 2048m

Step 2: Configure Kubernetes Resource Limits

For Kubernetes deployments, apply resource constraints and session configuration:

Before:

# clw-auth-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: clw-auth
spec:
  replicas: 2
  template:
    spec:
      containers:
      - name: clw-auth
        image: openclaw/auth-service:latest
        ports:
        - containerPort: 8443
        # No resource limits specified

After:

# clw-auth-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: clw-auth
spec:
  replicas: 2
  template:
    spec:
      containers:
      - name: clw-auth
        image: openclaw/auth-service:latest
        ports:
        - containerPort: 8443
        resources:
          requests:
            memory: "512Mi"
            cpu: "250m"
          limits:
            memory: "2Gi"
            cpu: "1000m"
        env:
        - name: CLAW_SESSION_MAX_AGE
          value: "3600"
        - name: CLAW_SESSION_CACHE_MAX_SIZE
          value: "10000"
        - name: CLAW_SESSION_EVICTION_POLICY
          value: "LRU"
        livenessProbe:
          httpGet:
            path: /health
            port: 8443
          initialDelaySeconds: 30
          periodSeconds: 10
        readinessProbe:
          httpGet:
            path: /ready
            port: 8443
          initialDelaySeconds: 10
          periodSeconds: 5

Step 3: Configure Session Cache Limits

Modify the OpenClaw configuration to enforce session cache limits:

Before:

{
  "authentication": {
    "service": {
      "port": 8443,
      "host": "0.0.0.0"
    },
    "session": {
      "cache": {
        "enabled": true
      }
    }
  }
}

After:

{
  "authentication": {
    "service": {
      "port": 8443,
      "host": "0.0.0.0"
    },
    "session": {
      "max_age": 3600,
      "cache": {
        "enabled": true,
        "max_size": 10000,
        "eviction_policy": "lru",
        "ttl_seconds": 1800,
        "cleanup_interval": 60
      }
    },
    "memory": {
      "max_heap_size": "1536M",
      "gc_frequency": "30s"
    }
  }
}

Step 4: Patch Memory Leak in Session Handler (⚠️ Unverified)

If the issue persists after increasing limits, a memory leak may be present. Apply the following patch to the session handler:

# session_handler.py - Before (leaky code)
class SessionCache:
    def __init__(self):
        self.cache = {}
    
    def store_session(self, session_id, session_data):
        # Memory leak: sessions stored but never cleaned
        self.cache[session_id] = session_data
    
    def get_session(self, session_id):
        return self.cache.get(session_id)

# session_handler.py - After (fixed code)
import time
import threading
from collections import OrderedDict

class SessionCache:
    def __init__(self, max_size=10000, ttl_seconds=1800):
        self.cache = OrderedDict()
        self.max_size = max_size
        self.ttl_seconds = ttl_seconds
        self.lock = threading.Lock()
        self._start_cleanup_thread()
    
    def _start_cleanup_thread(self):
        def cleanup():
            while True:
                time.sleep(60)  # Run cleanup every 60 seconds
                self._evict_expired()
        
        thread = threading.Thread(target=cleanup, daemon=True)
        thread.start()
    
    def _evict_expired(self):
        current_time = time.time()
        with self.lock:
            expired = [
                sid for sid, data in self.cache.items()
                if current_time - data['created_at'] > self.ttl_seconds
            ]
            for sid in expired:
                del self.cache[sid]
    
    def store_session(self, session_id, session_data):
        with self.lock:
            if len(self.cache) >= self.max_size:
                self.cache.popitem(last=False)  # Evict oldest (LRU)
            session_data['created_at'] = time.time()
            self.cache[session_id] = session_data
            self.cache.move_to_end(session_id)  # Update access order
    
    def get_session(self, session_id):
        with self.lock:
            data = self.cache.get(session_id)
            if data and (time.time() - data['created_at']) <= self.ttl_seconds:
                self.cache.move_to_end(session_id)  # Update access order
                return data
            elif data:
                del self.cache[session_id]  # Expired, remove it
        return None

Step 5: Verify System Swap Configuration

Ensure adequate swap space is available to handle temporary memory pressure:

# Check current swap configuration
swapon --show

# If swap is not configured or is insufficient, add swap file
sudo fallocate -l 2G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile

# Add to /etc/fstab for persistence
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

4. Verification

After implementing fixes, verify that the clw-auth-oom error is resolved by performing the following checks:

Health Check Endpoint:

curl -X GET http://localhost:8443/health

Expected response:

{
  "status": "healthy",
  "memory_usage": {
    "used_mb": 512,
    "limit_mb": 2048,
    "percent": 25
  },
  "session_cache": {
    "active_sessions": 3421,
    "max_capacity": 10000
  }
}

Load Testing Verification:

# Run authentication load test
clw-cli auth load-test \
  --concurrent-users 100 \
  --duration 300 \
  --target http://localhost:8443

# Expected: No OOM errors, successful completion
# VERIFY: Check logs for clw-auth-oom entries
grep "clw-auth-oom" /var/log/clw-auth/auth.log
# Expected: No matches after fix

Memory Monitoring:

# Monitor memory usage over 10 minutes
watch -n 5 'docker stats clw-auth --no-stream'

# Verify memory stays within limits
# Expected: Memory usage < 80% of limit under normal load

Session Cache Statistics:

curl -X GET http://localhost:8443/metrics | grep session

# Expected output:
# clw_session_cache_size 3421
# clw_session_cache_evictions_total 0
# clw_session_memory_bytes 67108864

5. Common Pitfalls

Pitfall 1: Increasing Limits Without Session Configuration Many administrators simply increase Docker or Kubernetes memory limits without configuring session cache bounds. This may delay the error but will not prevent future OOM conditions under high load. Always configure both resource limits and application-level session constraints.

Pitfall 2: Misunderstanding Container Memory Behavior Docker containers do not swap to disk when under memory pressure—they are immediately killed by the OOM killer. Setting mem-swappiness does not apply within containers. Always ensure memory limits are generous enough for peak load plus 20% buffer.

Pitfall 3: Ignoring the Difference Between Requests and Limits In Kubernetes, requests define the guaranteed minimum resources, while limits define the maximum. Setting limits too close to requests can cause throttling or termination under burst load. Set requests to 50% of limits to allow for proper resource elasticity.

Pitfall 4: Session Cache Size vs. Session Count The session cache max_size parameter limits the number of active session entries, not the total memory consumed. Large token payloads or extensive user claims can still cause OOM even with a small session count. Monitor actual memory usage and adjust heap size accordingly.

Pitfall 5: Inadequate Health Probe Timeouts Health probes that timeout too quickly may cause Kubernetes to restart pods prematurely, creating a cascading restart scenario. Set failureThreshold to at least 3 and timeoutSeconds to at least 5 for both liveness and readiness probes.

Pitfall 6: Not Restarting Services After Configuration Changes Configuration changes require service restart to take effect. Partial rollouts that only update configuration files without restarting pods leave the system in a mixed state. Always perform rolling restarts after configuration changes:

kubectl rollout restart deployment/clw-auth

clw-auth-timeout Authentication requests timeout before completion, often indicating resource contention or excessive session lookup latency. Related to clw-auth-oom in that both can result from overloaded authentication services, but clw-auth-timeout occurs under memory pressure rather than memory exhaustion.

clw-auth-crash The authentication service terminates unexpectedly without producing an OOM error message. May occur due to segfaults, assertion failures, or signals unrelated to memory exhaustion. Investigate core dumps to differentiate from clw-auth-oom.

clw-svc-oom General-purpose error indicating any OpenClaw service has exhausted memory, not specific to authentication. The fix for clw-svc-oom in non-auth services differs from clw-auth-oom as session cache configuration is authentication-specific.

clw-session-overflow Session cache reaches configured maximum capacity, causing new session creation to fail. This error typically precedes clw-auth-oom when the cache continues growing despite reaching the overflow threshold. Address by configuring smaller session TTL values or implementing session cleanup.

clw-auth-503 Service unavailable errors during authentication operations, often a downstream consequence of clw-auth-oom. When the authentication service crashes, upstream proxies return 503 while attempting to route requests. Fixing clw-auth-oom resolves the 503 errors.

1. Symptoms

2. Root Cause

3. Step-by-Step Fix

Step 1: Increase Container Memory Limits (Docker)

Step 2: Configure Kubernetes Resource Limits

Step 3: Configure Session Cache Limits

Step 4: Patch Memory Leak in Session Handler (⚠️ Unverified)

Step 5: Verify System Swap Configuration

4. Verification

5. Common Pitfalls

6. Related Errors