Job options (delay, attempts, priority) in NestJS - Step-by-Step Execution

Concept Flow - Job options (delay, attempts, priority)

Create Job with Options

↓

Set delay timer?

Yes→Wait delay ms

↓

Delay expires

↓

Add job to queue

↓

Start job processing

↓

Process job

↓

Job succeeds

↓

Check attempts left

↓

Done

No Yes↓

Fail

↓

Process job again

This flow shows how a job is created with options like delay, attempts, and priority, then processed with retries if it fails.

Execution Sample

NestJS

queue.add('email', { to: '[e-mail]' }, { delay: 5000, attempts: 3, priority: 2 });

Adds an email job to the queue with a 5-second delay, up to 3 retry attempts, and priority level 2.

Execution Table

Step	Action	Delay Timer	Attempts Left	Priority	Job Status
1	Job created with options	5000 ms	3	2	Waiting
2	Delay expires after 5000 ms	0 ms	3	2	Ready to process
3	Job processing starts	0 ms	3	2	Processing
4	Job fails	0 ms	2	2	Retrying
5	Job processing retry 1	0 ms	2	2	Processing
6	Job fails again	0 ms	1	2	Retrying
7	Job processing retry 2	0 ms	1	2	Processing
8	Job succeeds	0 ms	1	2	Completed

💡 Job succeeds at step 8 or fails after all attempts are used.

Variable Tracker

Variable	Start	After Step 2	After Step 4	After Step 6	After Step 8
delay	5000	0	0	0	0
attempts	3	3	2	1	1
priority	2	2	2	2	2
jobStatus	Waiting	Ready to process	Retrying	Retrying	Completed

Key Moments - 3 Insights

Why does the job wait before processing?

Because the delay option is set to 5000 ms, the job waits that time before starting processing, as shown in execution_table step 2.

What happens when a job fails but has attempts left?

The job retries processing, decreasing attempts by 1 each time, as seen in steps 4 and 6 where attempts go from 3 to 2 and then 1.

Does priority affect retry attempts?

No, priority stays the same during retries and only affects job order in the queue, not the number of attempts, as shown in variable_tracker.

Visual Quiz - 3 Questions

Look at the execution_table, what is the jobStatus at step 3?

A Processing

B Waiting

C Retrying

D Completed

💡 Hint

Check the 'Job Status' column in execution_table row with Step 3.

At which step does the delay timer reach zero?

A Step 1

B Step 2

C Step 4

D Step 8

💡 Hint

Look at the 'Delay Timer' column in execution_table to find when it changes from 5000 ms to 0 ms.

If attempts were set to 1 initially, how many retries would the job have?

A 3 retries

B 1 retry

C No retries

D 2 retries

💡 Hint

Refer to the 'Attempts Left' column in variable_tracker and how it decreases on failure.

Concept Snapshot

Job options in NestJS queues:
- delay: wait before processing (ms)
- attempts: retry count on failure
- priority: job order in queue
Jobs wait delay, then process.
Failures retry until attempts run out.

Full Transcript

This visual execution shows how NestJS job options delay, attempts, and priority work. A job is created with these options. The delay causes the job to wait before processing. When processing starts, if the job fails, it retries until attempts are used up. Priority affects job order but not retries. The execution table tracks each step, showing delay timer, attempts left, priority, and job status. Variable tracker shows how these values change over time. Key moments clarify common confusions about delay waiting, retry logic, and priority's role. The quiz tests understanding by referencing specific steps and variable states.