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213 lines
9.5 KiB
Markdown
213 lines
9.5 KiB
Markdown
# tt
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[`tt` online tutorial](https://arthas.aliyun.com/doc/arthas-tutorials.html?language=en&id=command-tt)
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Check the `parameters`, `return values` and `exceptions` of the methods at different times.
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`watch` is a powerful command but due to its feasibility and complexity, it's quite hard to locate the issue effectively.
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In such difficulties, `tt` comes into play.
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With the help of `tt` (_TimeTunnel_), you can check the contexts of the methods at different times in execution history.
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## Usage
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### Start Demo
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Start `math-game` in [Quick Start](quick-start.md).
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### Record method calls
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```bash
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$ tt -t demo.MathGame primeFactors
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Press Ctrl+C to abort.
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Affect(class-cnt:1 , method-cnt:1) cost in 66 ms.
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INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD
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-------------------------------------------------------------------------------------------------------------------------------------
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1000 2018-12-04 11:15:38 1.096236 false true 0x4b67cf4d MathGame primeFactors
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1001 2018-12-04 11:15:39 0.191848 false true 0x4b67cf4d MathGame primeFactors
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1002 2018-12-04 11:15:40 0.069523 false true 0x4b67cf4d MathGame primeFactors
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1003 2018-12-04 11:15:41 0.186073 false true 0x4b67cf4d MathGame primeFactors
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1004 2018-12-04 11:15:42 17.76437 true false 0x4b67cf4d MathGame primeFactors
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```
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### Specify the max number of matched Classes
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```bash
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$ tt -t -m 1 demo.MathGame primeFactors
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Press Q or Ctrl+C to abort.
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Affect(class count:1 , method count:1) cost in 130 ms, listenerId: 1.
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INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD
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-------------------------------------------------------------------------------------------------------------------------------------
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1000 2022-12-25 19:41:45 2.629929 true false 0x3bf400 MathGame primeFactors
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1001 2022-12-25 19:41:55 0.146161 false true 0x3bf400 MathGame primeFactors
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```
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- `-t`
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record the calling context of the method `demo.MathGame primeFactors`
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- `-n 3`
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limit the number of the records (avoid overflow for too many records; with `-n` option, Arthas can automatically stop recording once the records reach the specified limit)
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- `-m 1`
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limit the number of matched Classes to avoid JVM suspending when too many matched Classes. The default value is 50.
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- Property
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| Name | Specification |
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| --------- | ---------------------------------------------- |
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| INDEX | the index for each call based on time |
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| TIMESTAMP | time to invoke the method |
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| COST(ms) | time cost of the method call |
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| IS-RET | whether method exits with normal return |
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| IS-EXP | whether method failed with exceptions |
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| OBJECT | `hashCode()` of the object invoking the method |
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| CLASS | class name of the object invoking the method |
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| METHOD | method being invoked |
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- Condition expression
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Tips:
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1. `tt -t *Test print params.length==1` with different amounts of parameters;
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2. `tt -t *Test print 'params[1] instanceof Integer'` with different types of parameters;
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3. `tt -t *Test print params[0].mobile=="13989838402"` with specified parameter.
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Advanced:
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- [Critical fields in expression](advice-class.md)
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- [Special usage](https://github.com/alibaba/arthas/issues/71)
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- [OGNL official guide](https://commons.apache.org/proper/commons-ognl/language-guide.html)
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### List all records
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```bash
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$ tt -l
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INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD
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-------------------------------------------------------------------------------------------------------------------------------------
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1000 2018-12-04 11:15:38 1.096236 false true 0x4b67cf4d MathGame primeFactors
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1001 2018-12-04 11:15:39 0.191848 false true 0x4b67cf4d MathGame primeFactors
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1002 2018-12-04 11:15:40 0.069523 false true 0x4b67cf4d MathGame primeFactors
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1003 2018-12-04 11:15:41 0.186073 false true 0x4b67cf4d MathGame primeFactors
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1004 2018-12-04 11:15:42 17.76437 true false 0x4b67cf4d MathGame primeFactors
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9
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1005 2018-12-04 11:15:43 0.4776 false true 0x4b67cf4d MathGame primeFactors
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Affect(row-cnt:6) cost in 4 ms.
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```
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### Searching for records
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```bash
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$ tt -s 'method.name=="primeFactors"'
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INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD
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-------------------------------------------------------------------------------------------------------------------------------------
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1000 2018-12-04 11:15:38 1.096236 false true 0x4b67cf4d MathGame primeFactors
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1001 2018-12-04 11:15:39 0.191848 false true 0x4b67cf4d MathGame primeFactors
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1002 2018-12-04 11:15:40 0.069523 false true 0x4b67cf4d MathGame primeFactors
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1003 2018-12-04 11:15:41 0.186073 false true 0x4b67cf4d MathGame primeFactors
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1004 2018-12-04 11:15:42 17.76437 true false 0x4b67cf4d MathGame primeFactors
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9
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1005 2018-12-04 11:15:43 0.4776 false true 0x4b67cf4d MathGame primeFactors
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Affect(row-cnt:6) cost in 607 ms.
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```
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Advanced:
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- [Critical fields in expression](advice-class.md)
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### Check context of the call
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Using `tt -i <index>` to check a specific calling details.
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```bash
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$ tt -i 1003
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INDEX 1003
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GMT-CREATE 2018-12-04 11:15:41
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COST(ms) 0.186073
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OBJECT 0x4b67cf4d
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CLASS demo.MathGame
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METHOD primeFactors
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IS-RETURN false
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IS-EXCEPTION true
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PARAMETERS[0] @Integer[-564322413]
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THROW-EXCEPTION java.lang.IllegalArgumentException: number is: -564322413, need >= 2
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at demo.MathGame.primeFactors(MathGame.java:46)
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at demo.MathGame.run(MathGame.java:24)
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at demo.MathGame.main(MathGame.java:16)
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Affect(row-cnt:1) cost in 11 ms.
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```
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### Replay record
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Since Arthas stores the context of the call, you can even _replay_ the method calling afterwards with extra option `-p` to replay the issue for advanced troubleshooting, option `--replay-times`
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define the replay execution times, option `--replay-interval` define the interval(unit in ms,with default value 1000) of replays
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```bash
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$ tt -i 1004 -p
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RE-INDEX 1004
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GMT-REPLAY 2018-12-04 11:26:00
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OBJECT 0x4b67cf4d
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CLASS demo.MathGame
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METHOD primeFactors
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PARAMETERS[0] @Integer[946738738]
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IS-RETURN true
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IS-EXCEPTION false
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RETURN-OBJ @ArrayList[
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@Integer[2],
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@Integer[11],
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@Integer[17],
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@Integer[2531387],
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]
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Time fragment[1004] successfully replayed.
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Affect(row-cnt:1) cost in 14 ms.
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```
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### Watch express
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`-w, --watch-express` watch the time fragment by ognl express.
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- You can used all variables in [fundamental fields in expressions](advice-class.md) for the watch express。
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```bash
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[arthas@10718]$ tt -t demo.MathGame run -n 5
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Press Q or Ctrl+C to abort.
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Affect(class count: 1 , method count: 1) cost in 56 ms, listenerId: 1
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INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD
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----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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1000 2021-01-08 21:54:17 0.901091 true false 0x7699a589 MathGame run
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[arthas@10718]$ tt -w 'target.illegalArgumentCount' -x 1 -i 1000
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@Integer[60]
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Affect(row-cnt:1) cost in 7 ms.
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```
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- Get a static field and calling a static method
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```bash
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[arthas@10718]$ tt -t demo.MathGame run -n 5
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Press Q or Ctrl+C to abort.
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Affect(class count: 1 , method count: 1) cost in 56 ms, listenerId: 1
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INDEX TIMESTAMP COST(ms) IS-RET IS-EXP OBJECT CLASS METHOD
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----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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1000 2021-01-08 21:54:17 0.901091 true false 0x7699a589 MathGame run
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[arthas@10718]$ tt -w '@demo.MathGame@random.nextInt(100)' -x 1 -i 1000
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@Integer[46]
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```
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Note that `com.taobao.arthas.core.advisor.Advice#getLoader` is used here, and that it is better to use the exact `classloader` [ognl](ognl.md).
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Advanced usage [get spring context to call the bean method](https://github.com/alibaba/arthas/issues/482)
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F.Y.I
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1. **Loss** of the `ThreadLocal`
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Arthas save params into an array, then invoke the method with the params again. The method execute in another thread, so the `ThreadLocal` **lost**.
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2. params may be modified
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Arthas save params into an array, they are object references. The Objects may be modified by other code.
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