A data scientist runs the exhibit AWS Glue ETL job. The job fails with a Spark stage failure error. What is the most likely cause?
Casting string to double fails on non-numeric data, causing task failure.
Why this answer
The Spark stage failure error in an AWS Glue ETL job is most likely caused by a data type mismatch during the ApplyMapping transformation. When the 'value' column contains non-numeric strings that cannot be cast to double, Spark throws a stage failure because it cannot complete the required type conversion, leading to task failures and job termination.
Exam trap
The trap here is that candidates often attribute Spark stage failures to resource issues (memory or missing paths) rather than recognizing that data type casting errors during transformations are a primary cause of stage-level failures in Glue ETL jobs.
How to eliminate wrong answers
Option A is wrong because a missing output path would cause a different error, such as 'Path does not exist' or 'FileNotFoundException', not a Spark stage failure. Option B is wrong because a non-existent S3 bucket would result in an 'AccessDenied' or 'NoSuchBucket' error at the job start, not during a Spark stage. Option C is wrong because insufficient memory typically manifests as an 'OutOfMemoryError' or 'Container killed by YARN' error, not a generic stage failure; stage failures are more commonly tied to data processing errors like type casting issues.