Simulate JVM Application Faults

Throw custom exceptions
Trigger garbage collection
Increase method latency
Modify return values of a method
Trigger faults by setting Byteman configuration files
Increase JVM pressure

This document describes how to use Chaosd to create the above fault types of JVM experiments.

This section introduces how to create the experiments of JVM application faults using the command-line mode.

Before creating the experiment, you can run the following command line to see the types of JVM application faults supported by Chaosd:

The result is as follows:


Usage:
  chaosd attack jvm [command]
Available Commands:
  exception   throw specified exception for specified method
  gc          trigger GC for JVM
  latency     inject latency to specified method
  return      return specified value for specified method
  rule-file   inject fault with configured byteman rule file
  stress      inject stress to JVM
Flags:
  -h, --help       help for jvm
      --pid int    the pid of Java process which needs to attach
      --port int   the port of agent server (default 9288)
Global Flags:
      --log-level string   the log level of chaosd. The value can be 'debug', 'info', 'warn' and 'error'
      --uid string         the experiment ID
Use "chaosd attack jvm [command] --help" for more information about a command.

Commands for throwing custom exceptions

To see the usage and configuration items of the command that throws custom exceptions, run the following command:

The result is as follows:

throw specified exception for specified method
Usage:
  chaosd attack jvm exception [options] [flags]
Flags:
  -c, --class string       Java class name
      --exception string   the exception which needs to throw for action 'exception'
  -h, --help               help for exception
  -m, --method string      the method name in Java class
Global Flags:
      --log-level string   the log level of chaosd. The value can be 'debug', 'info', 'warn' and 'error'
      --pid int            the pid of Java process which needs to attach
      --port int           the port of agent server (default 9288)
      --uid string         the experiment ID

Configuration description for throwing custom exceptions

Example for throwing custom exceptions

chaosd attack jvm exception -c Main -m sayhello --exception 'java.io.IOException("BOOM")' --pid 30045

The result is as follows:

[2021/08/05 02:39:39.106 +00:00] [INFO] [jvm.go:208] ["byteman rule"] [rule="\nRULE Main-sayhello-exception-q6nd0\nCLASS Main\nMETHOD sayhello\nAT ENTRY\nIF true\nDO \n\tthrow new java.io.IOException(\"BOOM\");\nENDRULE\n"] [file=/tmp/rule.btm296930759]
Attack jvm successfully, uid: 26a45ae2-d395-46f5-a126-2b2c6c85ae9d

Trigger garbage collection using the command-line mode

Commands for triggering garbage collection

To see the usage and configuration items of the command that triggers garbage collection, run the following command:

chaosd attack jvm gc --help

trigger GC for JVM
Usage:
  chaosd attack jvm gc [flags]
Flags:
  -h, --help   help for gc
Global Flags:
      --log-level string   the log level of chaosd. The value can be 'debug', 'info', 'warn' and 'error'
      --pid int            the pid of Java process which needs to attach
      --port int           the port of agent server (default 9288)
      --uid string         the experiment ID

Configuration description for triggering garbage collection

Configuration item	Abbreviation	Description	Value
`pid`	None	The Java process ID where the fault is to be injected	int type, required
`port`	None	The port number attached to the Java process agent. The fault is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	None	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for triggering garbage collection

chaosd attack jvm gc --pid 89345

The result is as follows:

[2021/08/05 02:49:47.850 +00:00] [INFO] [jvm.go:208] ["byteman rule"] [rule="\nRULE --gc-u0mlf\nGC\nENDRULE\n"] [file=/tmp/rule.btm012481052]
Attack jvm successfully, uid: f360e70a-5359-49b6-8526-d7e0a3c6f696

Triggering garbage collection is a one-time operation, and the experiment does not require recovery.

Increase method latency using the command-line mode

Commands for increasing method latency

To see the usage and configuration items of the command that increases method latency, run the following command:

chaosd attack jvm latency --help

The result is as follows:

inject latency to specified method
Usage:
  chaosd attack jvm latency [options] [flags]
Flags:
  -c, --class string    Java class name
  -h, --help            help for latency
      --latency int     the latency duration, unit ms
  -m, --method string   the method name in Java class
Global Flags:
      --log-level string   the log level of chaosd. The value can be 'debug', 'info', 'warn' and 'error'
      --port int           the port of agent server (default 9288)
      --uid string         the experiment ID

Configuration description for increasing method latency

Configuration item	Abbreviation	Description	Value
`class`	`c`	The name of the Java class	string type, required
`latency`	None	The duration of increasing method latency	int type, required. The unit is milisecond.
`method`	`m`	The name of the method	string type, required
`pid`	None	The Java process ID where the fault is to be injected	int type, required
`port`	None	The port number attached to the Java process agent. The fault is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	None	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for increasing method latency

chaosd attack jvm latency --class Main --method sayhello --latency 5000 --pid 100840

[2021/08/05 03:08:50.716 +00:00] [INFO] [jvm.go:208] ["byteman rule"] [rule="\nRULE Main-sayhello-latency-hlib2\nCLASS Main\nMETHOD sayhello\nAT ENTRY\nIF true\nDO \n\tThread.sleep(5000);\nENDRULE\n"] [file=/tmp/rule.btm359997255]
[2021/08/05 03:08:51.155 +00:00] [INFO] [jvm.go:94] ["submit rules"] [output="install rule Main-sayhello-latency-hlib2\n\n"]
Attack jvm successfully, uid: bbe00c57-ac9d-4113-bf0c-2a6f184be261

Modify return values of a method using the command-line mode

Commands for modifying return values of a method

To see the usage and configuration items of the command that modifies return values of a method, run the following command:

return specified value for specified method
Usage:
  chaosd attack jvm return [options] [flags]
Flags:
  -c, --class string    Java class name
  -h, --help            help for return
  -m, --method string   the method name in Java class
      --value string    the return value for action 'return'. Only supports number and string types.
Global Flags:
      --log-level string   the log level of chaosd. The value can be 'debug', 'info', 'warn' and 'error'
      --pid int            the pid of Java process which needs to attach
      --port int           the port of agent server (default 9288)
      --uid string         the experiment ID

Configuration description for modifying return values of a method

Configuration item	Abbreviation	Description	Value
class	c	The name of the Java class	string type, required to be configured
method	m	The name of the method	string type, required to be configured
value	None	Specifies the return value of the method	string type, required to be configured. Currently, the item can be numeric and string types. If the item (return value) is string, double quotes are required, like “chaos”.
pid	None	The Java process ID where the fault is needed to be injected	int type, required to be configured
port	None	The port number attached to the Java process agent. The faults is injected into the Java process through this port number.	int type. The default value is `9288`.
uid	None	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for simulating the scenario of modifying return values of a method

The result is as follows:

[2021/08/05 03:35:10.603 +00:00] [INFO] [jvm.go:208] ["byteman rule"] [rule="\nRULE Main-getnum-return-i6gb7\nCLASS Main\nMETHOD getnum\nAT ENTRY\nIF true\nDO \n\treturn 999;\nENDRULE\n"] [file=/tmp/rule.btm051982059]
[2021/08/05 03:35:10.820 +00:00] [INFO] [jvm.go:94] ["submit rules"] [output="install rule Main-getnum-return-i6gb7\n\n"]
Attack jvm successfully, uid: e2f204f6-4bed-4d92-aade-2b4a47b02e5d

You can set the fault rules in the Byteman rule configuration file, and then inject the faults by specifying the path of the configuration file using Chaosd. Regarding the Byteman rule configuration, refer to byteman-rule-language.

Commands for triggering faults by setting Byteman configuration files

To see the usage and configuration items of the command that triggers faults by setting Byteman configuration files, run the following command:

chaosd attack jvm rule-file --help

The result is as follows:

inject fault with configured byteman rule file
Usage:
  chaosd attack jvm rule-file [options] [flags]
Flags:
  -h, --help          help for rule-file
  -p, --path string   the path of configured byteman rule file
Global Flags:
      --log-level string   the log level of chaosd, the value can be 'debug', 'info', 'warn' and 'error'
      --pid int            the pid of Java process which needs to attach
      --port int           the port of agent server (default 9288)
      --uid string         the experiment ID

Configuration description for triggering faults by setting Byteman configuration files

Example for triggering faults by setting Byteman configuration files

First, based on the specific Java program and referring to the Byteman rule language, write a rule configuration file. For example:

RULE modify return value
CLASS Main
METHOD getnum
AT ENTRY
IF true
DO
    return 9999
ENDRULE

Then, save the configuration file to the return.btm file. After that, run the following command to inject faults.

chaosd attack jvm rule-file -p ./return.btm --pid 112694

The result is as follows:

[2021/08/05 03:45:40.757 +00:00] [INFO] [jvm.go:152] ["rule file data:RULE modify return value\nCLASS Main\nMETHOD getnum\nAT ENTRY\nIF true\nDO\n    return 9999\nENDRULE\n"]
[2021/08/05 03:45:41.011 +00:00] [INFO] [jvm.go:94] ["submit rules"] [output="install rule modify return value\n\n"]
Attack jvm successfully, uid: 5ca2e06d-a7c6-421d-bb67-0c9908bac17a

Increase JVM stress using the command-line mode

Commands for increasing JVM stress

To see the usage and configuration items of the command that increases JVM stress, run the following command:

chaosd attack jvm stress --help

The result is as follows:

inject stress to JVM
Usage:
  chaosd attack jvm stress [options] [flags]
Flags:
      --cpu-count int   the CPU core number
  -h, --help            help for stress
      --mem-type int    the memory type to be allocated. The value can be 'stack' or 'heap'.
Global Flags:
      --log-level string   the log level of chaosd. The value can be 'debug', 'info', 'warn' and 'error'
      --pid int            the pid of Java process which needs to attach
      --uid string         the experiment ID

Configuration description for increasing JVM stress

Configuration item	Abbreviation	Description	Value
`cpu-count`	None	The number of CPU cores used for increasing JVM stress	int type. You must configure one item between `cpu-count` and `mem-type`.
`mem-type`	None	The type of OOM	string type. Currently, both ‘stack’ and ‘heap’ OOM types are supported. You must configure one item between `cpu-count` and `mem-type`.
`pid`	None	The Java process ID where the fault is to be injected	int type, required
`port`	None	The port number attached to the Java process agent. The fault is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	None	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for increasing JVM stress

chaosd attack jvm stress --cpu-count 2 --pid 123546

The result is as follows:

[2021/08/05 03:59:51.256 +00:00] [INFO] [jvm.go:208] ["byteman rule"] [rule="\nRULE --stress-jfeiu\nSTRESS CPU\nCPUCOUNT 2\nENDRULE\n"] [file=/tmp/rule.btm773062009]
[2021/08/05 03:59:51.613 +00:00] [INFO] [jvm.go:94] ["submit rules"] [output="install rule --stress-jfeiu\n\n"]
Attack jvm successfully, uid: b9b997b5-0a0d-4f1f-9081-d52a32318b84

Create experiments using the service mode

You can follow the instructions below to create experiments using the service mode.

```
chaosd server --port 31767
```
Send HTTP POST request to the /api/attack/{uid} path of Chaosd service.

For the fault-configuration part in the above command, you need to configure it according to the fault types. For the corresponding parameters, refer to the parameters and examples of each fault type in the following sections.

note

When running an experiment, remember to save the UID information of the experiment. When you want to end the experiment corresponding to the UID, you need to send an HTTP DELETE request to the /api/attack/{uid} path of Chaosd service.

Throw custom exceptions using the service mode

Parameters for throwing custom exceptions

Parameter	Description	Value
`action`	The action of the experiment	Set to “exception”
`class`	The name of the Java class	string type, required
`exception`	The thrown custom exception	string type, required
`method`	The name of the method	string type, required
`pid`	The Java process ID where the fault is to be injected	int type, required
`port`	The port number attached to the Java process agent. The faults is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for throwing custom exceptions using the service mode

curl -X POST 172.16.112.130:31767/api/attack/jvm -H "Content-Type:application/json" -d '{"action":"exception","class":"Main","method":"sayhello","exception":"java.io.IOException(\"BOOM\")","pid":1828622}'

The result is as follows:

{"status":200,"message":"attack successfully","uid":"c3c519bf-819a-4a7b-97fb-e3d0814481fa"}

Trigger garbage collection using service mode

Parameters for triggering garbage collection

Parameter	Description	Value
`action`	The action of the experiment	Set to “gc”
`pid`	The Java process ID where the fault is to be injected	int type, required
`port`	The port number attached to the Java process agent. The fault is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for triggering garbage collection using the service mode

curl -X POST 172.16.112.130:31767/api/attack/jvm -H "Content-Type:application/json" -d '{"action":"gc","pid":1828622}'

The result is as follows:

{"status":200,"message":"attack successfully","uid":"c3c519bf-819a-4a7b-97fb-e3d0814481fa"}

Triggering garbage collection is a one-time operation. The experiment does not require recovery.

Parameters for increasing method latency

Example for increasing method latency using the service mode

curl -X POST 172.16.112.130:31767/api/attack/jvm -H "Content-Type:application/json" -d '{"action":"latency","class":"Main","method":"sayhello","latency":5000,"pid":1828622}'

The result is as follows:

{"status":200,"message":"attack successfully","uid":"a551206c-960d-4ac5-9056-518e512d4d0d"}

Modify return values of a method using service mode

Parameters for modifying return values of a method

Parameter	Description	Value
`action`	The action of the experiment	Set to “return”
`class`	The name of the Java class	string type, required
`method`	The name of the method	string type, required
`value`	Specifies the return value of the method	string type, required. Currently, the item can be numeric and string types. If the item (return value) is string, double quotes are required, like “chaos”.
`pid`	The Java process ID where the fault is to be injected	int type, required
`port`	The port number attached to the Java process agent. The fault is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for modifying return values of a method using the service mode

curl -X POST 172.16.112.130:31767/api/attack/jvm -H "Content-Type:application/json" -d '{"action":"return","class":"Main","method":"getnum","value":"999","pid":1828622}'

The result is as follows:

{"status":200,"message":"attack successfully","uid":"a551206c-960d-4ac5-9056-518e512d4d0d"}

Trigger faults by setting Byteman configuration files using service mode

You can set the fault rules according to the Byteman rule configuration. Regarding to the Byteman rule configuration, refer to .

Parameters for triggering faults by setting Byteman configuration files

Parameter	Description	Value
`action`	The action of the experiment	Set to “rule-data”
`rule-data`	Specifies the Byteman configuration data	string type, required
`pid`	The Java process ID where the fault is to be injected	int type, required
`port`	The port number attached to the Java process agent. The fault is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for triggering faults by setting Byteman configuration files using the service mode

First, based on the specific Java program and referring to the Byteman rule language, write a rule configuration file. For example:

RULE modify return value
CLASS Main
METHOD getnum
AT ENTRY
IF true
DO
    return 9999
ENDRULE

Then, escape the line breaks in the configuration file to the newline character “\n”, and use the escaped text as the value of “rule-data”. Run the following command:

curl -X POST 127.0.0.1:31767/api/attack/jvm -H "Content-Type:application/json" -d '{"action":"rule-data","pid":30045,"rule-data":"\nRULE modify return value\nCLASS Main\nMETHOD getnum\nAT ENTRY\nIF true\nDO return 9999\nENDRULE\n"}'

{"status":200,"message":"attack successfully","uid":"a551206c-960d-4ac5-9056-518e512d4d0d"}

Increase JVM stress using the service mode

Parameters for increasing JVM stress

Parameter	Description	Value
`action`	The action of the experiment	Set to “stress”
`cpu-count`	The number of CPU cores used for increasing CPU stress	int type. You must configure one item between `cpu-count` and `mem-type`.
`mem-type`	The type of OOM	string type. Currently, both ‘stack’ and ‘heap’ OOM types are supported. You must configure one item between `cpu-count` and `mem-type`.
`pid`	None	The Java process ID where the fault is to be injected	int type, required
`port`	None	The port number attached to the Java process agent. The fault is injected into the Java process through this port number.	int type. The default value is `9288`.
`uid`	None	The experiment ID	string type. This item is not required to be configured, because Chaosd randomly creates one.

Example for increasing JVM stress using the service mode

curl -X POST 172.16.112.130:31767/api/attack/jvm -H "Content-Type:application/json" -d '{"action":"stress","cpu-count":1,"pid":1828622}'

The result is as follows: