Optimize Batch startup time

Batch needs Compute environments to run the Jobs. RUNNABLE jobs are started as soon as sufficient resources are available in one of the compute environments that are mapped to the job's queue. Now Compute Env can be unavailable due to various factors like non availability of selected Spot instances at that moment or you choose an single AZ where on demand capacity is very thin ( think specialized instances)

Additionally, the AWS Batch Scheduler periodically evaluates jobs in the queue and moves them forward as appropriate. As you submit more jobs, you will see that the AWS Batch Scheduler evaluates and operates upon many jobs at once with each scheduling interval.

For example, if you submit a hundred jobs to AWS Batch, the Scheduler will transition all of these from SUBMITTED to RUNNABLE or PENDING in about a minute. RUNNABLE jobs should transition to STARTING and RUNNING fairly quickly assuming you have sufficient resources in your compute environment.

Here are some resources to debug : Why is my AWS Batch job stuck in RUNNABLE status?

Some Blog : AWS Batch Dos and Don’ts: Best Practices in a Nutshell