Logview is a tool that you can use to view and debug jobs after you submit jobs to MaxCompute.
- Running status of tasks
- Running results of tasks
- Details of each task and the progress of each step
- ODPS Instance
- ODPS Tasks
- You can click the value in the Status column to view queue information. Valid values
Note If the value of Status is Terminated, the job has been terminated and no queue information is available.
- Waiting: The job is being processed in MaxCompute and has not been submitted to Job Scheduler.
- Waiting List: n: The job has been submitted to Job Scheduler and is queued. n indicates the order number of the job in the queue.
- Running: The job is running in Job Scheduler.
- After you click the value of Status, the following queue information is displayed:
- Sub Status: the current sub-status information.
- WaitPos: the position of the job in the queue. The value
0indicates that the job is running. The value
-indicates that the job has not been submitted to Job Scheduler.
- QueueLength: the total queue length in Job Scheduler.
- Total Priority: the running priority assigned by the system.
- SubStatus History: You can click the icon in this column to view the status history. This includes the status code, status description, start time, and duration of a state. The information is unavailable in some versions.
The ODPS Tasks section shows the information of the task that corresponds to the instance. The information includes Name, Type, Status, Result, Detail, StartTime, EndTime, Latency (s), and TimeLine. Like on other pages, Latency (s) indicates the running duration.
- A MaxCompute job consists of one or more Fuxi jobs. For example, if a complex SQL job is submitted, MaxCompute automatically submits multiple Fuxi jobs to Job Scheduler.
- Each Fuxi job consists of one or more Fuxi tasks. For example, a simple MapReduce job generates two Fuxi tasks: Map Task (M1) and Reduce Task (R2). If an SQL statement is complex, multiple Fuxi tasks may be generated.
- The name of a Fuxi task. In most cases, a task name consists of letters and digits.
A letter represents the type of a task, such as M for a map task. The digits that
follow the letter represents the ID and dependencies of a task. For example, R5_4
indicates that the reduce task can be executed only after the J4 task is completed.
J4_1_2_3 indicates that the join task can be executed only after the M1, M2, and M3
tasks are completed.
Note I/O Records indicates the numbers of the input and output records of a Fuxi task.
- I/O Records indicates the numbers of the input and output records of this task.
Use Logview to handle issues
- Tasks with errors
If an error occurs during a task, find the task and click the icon in the Result column in the lower part of the Logview page to view the error information. You can also click the icon in the StdErr column of a Fuxi instance in the details dialog box to view the error information of the instance.
- Data skew
The long tail of one or more Fuxi instances may decelerate the execution of a Fuxi task. The long tail is caused by uneven data distribution in a task. After a task is completed, you can view the running results on the Summary tab of the details dialog box. The following output provides an example of the running results.
output records: R2_1_Stg1: 199998999 (min: 22552459, max: 177446540, avg: 99999499)
If the difference between the min and max values is large, data skew occurs. For example, if a specific value appears more often than other values in a column, data skew occurs when you execute a JOIN operation based on this column.