sentry-jstack

Retrieves a full thread dump from a remote sentry. Use this command to remotely diagnose the internal operational state of a logger.

Command properties

Property	Description
Command type	Transforming
Required permission	Administrator
License usage	N/A
Parallel execution	Supported
Distributed execution	Not supported

Syntax

sentry-jstack [timeout=INT]

Options

timeout=INT: RPC timeout in seconds. Accepts a value between 1 and 600. (Default: 30)

Input fields

Field	Type	Required	Description
guid	string	Required	Sentry unique identifier.

Output fields

Field	Type	Description
guid	string	Sentry unique identifier.
tid	long	Thread ID.
name	string	Thread name.
state	string	Thread state.
stacktrace	string	Thread stack trace.
_error	string	Error message if an error occurred.

Possible values for the state field:

Value	Description
RUNNABLE	A thread that can run at any time.
BLOCKED	A thread waiting for an object's lock to be released.
TIMED_WAITING	A thread waiting for a specified period of time.
WAITING	A thread waiting to synchronize with another thread.

Error codes

Parsing errors

Error code	Message	Description
23100	No permission to call sentry RPC.	A user without administrator privileges ran the command.
23101	Invalid sentry RPC timeout option value. Use a value between 1 and 600.	The `timeout` option value is not a number or is outside the range 1–600.

Runtime errors

Depending on the guid field value, the following error messages may be assigned to the _error field:

Error message	Description
guid is null	The `guid` field value in the input record is null.
guid should be string	The `guid` field value in the input record is not a string.
guid should be non empty string	The `guid` field value in the input record is an empty string.
not connected	The sentry is not connected.
timeout	The RPC request timed out.
disconnected	The connection was lost while processing the RPC request.

Other RPC exception messages may be assigned to the _error field depending on the state of the system where the sentry is installed.

Description

The sentry-jstack command sends asynchronous RPC messages requesting a full thread dump to remote sentries identified by the guid field of each input record. When a response is received from a sentry, the thread information is added to the input record and output.

The maximum length of the asynchronous RPC request queue is 100 by default and can be adjusted using the logpresso.core.sentry_rpc_parallel environment variable. When the queue is full and some sentries respond or time out, new RPC messages are sent to fill the freed slots.

Results are output in the order RPC responses are received, so the output record order may differ from the input record order.

To retrieve results from all Data Nodes at once in a cluster environment, use the sonar-sentry-jstack command.

Examples

Retrieve a thread dump from all sentries
```
system sentries | fields guid | sentry-jstack
```
Retrieves a full thread dump from all connected sentries.
Retrieve only BLOCKED threads
```
system sentries | fields guid | sentry-jstack | search state == "BLOCKED"
```
Filters only threads in the BLOCKED state from all sentries.