ENABLE_PREFETCH_DAEMON

Whether to enable prefetch of DockerDaemon by default.

This option moves the allocation of DockerDaemon to the constructor of DockerRunner instead of during execWithInput. Setting this field to true uses the legacy behavior where the daemon is allocated in the constructor via a spinlock.

In practice, this will likely provide no significant performance improvement, as most usages of DockerRunner invokes execWithInput immediately after the constructor is invoked.