AWS Lambda
Developer Guide

The AWS X-Ray Daemon in the Lambda Environment

The AWS X-Ray Daemon is a software application that gathers raw segment data and relays it to the AWS X-Ray service. The daemon works in conjunction with the AWS X-Ray SDKs so that data sent by the SDKs can reach the X-Ray service.

When you trace your Lambda function, the X-Ray daemon automatically runs in the Lambda environment to gather trace data and send it to X-Ray. When tracing, the X-Ray daemon consumes a maximum of 16 MB or 3 percent of your function's memory allocation. For example, if you allocate 128 MB of memory to your Lambda function, the X-Ray daemon has 16 MB of your function's memory allocation. If you allocate 1024 MB to your Lambda function, the X-Ray daemon has 31 MB allocated to it (3 percent). For more information, see The AWS X-Ray Daemon.

Note

Lambda will try to terminate the X-Ray daemon to avoid exceeding your function's memory limit. For example, assume you have allocated 128 MB to your Lambda function, which means the X-Ray daemon will have 16 MB allocated to it. That leaves your Lambda function with a memory allocation of 112 MB. However, if your function exceeds 112 MB, the X-Ray daemon will be terminated to avoid throwing an out-of-memory error.