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Posted to notifications@skywalking.apache.org by GitBox <gi...@apache.org> on 2021/04/07 03:46:41 UTC
[GitHub] [skywalking] BFergerson opened a new issue #6701: Redefinition support
BFergerson opened a new issue #6701:
URL: https://github.com/apache/skywalking/issues/6701
Please answer these questions before submitting your issue.
- Why do you submit this issue?
- [x] Feature or performance improvement
___
### Requirement or improvement
Calling `Instrumentation.retransformClasses())` on a class which SkyWalking has already enhanced will cause issues such as https://github.com/raphw/byte-buddy/issues/908. This issue boils down to SkyWalking not generating the same bytecode modifications each time it's called.
As an example, here is the loaded class after SkyWalking enhancements:
<details>
<summary>Decompiled source code</summary>
```java
package spp.example.webapp.controller;
import spp.example.webapp.service.*;
import org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.*;
import java.lang.reflect.*;
import spp.example.webapp.model.*;
import java.util.concurrent.*;
import org.springframework.web.bind.annotation.*;
import org.springframework.http.*;
import org.apache.skywalking.apm.toolkit.trace.*;
import org.slf4j.*;
@RestController
public class WebappController implements EnhancedInstance
{
private static final Logger log;
private final UserService userService = userService;
private volatile Object _$EnhancedClassField_ws;
public static volatile /* synthetic */ InstMethodsInter delegate$v1o0sl0;
public static volatile /* synthetic */ InstMethodsInter delegate$1p16ip1;
public static volatile /* synthetic */ ConstructorInter delegate$bn83ge1;
private static final /* synthetic */ Method cachedValue$5aQdBH3R$tcgf6s2;
private static final /* synthetic */ Method cachedValue$5aQdBH3R$551d7u2;
private static final /* synthetic */ Method cachedValue$5aQdBH3R$r5lbqa2;
private static final /* synthetic */ Method cachedValue$5aQdBH3R$pslu6e0;
private static final /* synthetic */ Method cachedValue$5aQdBH3R$tv4hlg2;
private static final /* synthetic */ Method cachedValue$5aQdBH3R$fe38712;
private static final /* synthetic */ Method cachedValue$5aQdBH3R$moqjd11;
public WebappController(final UserService userService) {
this(userService, null);
WebappController.delegate$bn83ge1.intercept((Object)this, new Object[] { userService });
}
@RequestMapping(value = { "/users" }, method = { RequestMethod.GET })
public ResponseEntity<Iterable<User>> userList() {
return (ResponseEntity<Iterable<User>>)WebappController.delegate$1p16ip1.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$rC0tNskD(this), WebappController.cachedValue$5aQdBH3R$tv4hlg2);
}
@RequestMapping(value = { "/users/{id}" }, method = { RequestMethod.GET })
public ResponseEntity<User> getUser(@PathVariable final long id) {
return (ResponseEntity<User>)WebappController.delegate$1p16ip1.intercept((Object)this, new Object[] { id }, (Callable)new WebappController$auxiliary$3VgxmlNG(this, id), WebappController.cachedValue$5aQdBH3R$fe38712);
}
@RequestMapping(value = { "/users" }, method = { RequestMethod.POST })
public ResponseEntity<User> createUser(@RequestParam final String firstName, @RequestParam final String lastName) {
return (ResponseEntity<User>)WebappController.delegate$1p16ip1.intercept((Object)this, new Object[] { firstName, lastName }, (Callable)new WebappController$auxiliary$giwk9nlQ(this, firstName, lastName), WebappController.cachedValue$5aQdBH3R$r5lbqa2);
}
@RequestMapping(value = { "/users" }, method = { RequestMethod.DELETE })
public void deleteUser(@RequestParam final String firstName, @RequestParam final String lastName) {
WebappController.delegate$1p16ip1.intercept((Object)this, new Object[] { firstName, lastName }, (Callable)new WebappController$auxiliary$TTasfNa2(this, firstName, lastName), WebappController.cachedValue$5aQdBH3R$pslu6e0);
}
@RequestMapping(value = { "/throws-exception" }, method = { RequestMethod.GET })
public void throwsException() {
WebappController.delegate$1p16ip1.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$dwKvz7iY(this), WebappController.cachedValue$5aQdBH3R$551d7u2);
}
@Trace
private void caughtException() {
WebappController.delegate$v1o0sl0.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$O6efGa79(this), WebappController.cachedValue$5aQdBH3R$moqjd11);
}
@Trace
private void uncaughtException() {
WebappController.delegate$v1o0sl0.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$7x058cxd(this), WebappController.cachedValue$5aQdBH3R$tcgf6s2);
}
static {
ClassLoader.getSystemClassLoader().loadClass("org.apache.skywalking.apm.dependencies.net.bytebuddy.dynamic.Nexus").getMethod("initialize", Class.class, Integer.TYPE).invoke(null, WebappController.class, -1316167843);
cachedValue$5aQdBH3R$tcgf6s2 = WebappController.class.getDeclaredMethod("uncaughtException", (Class<?>[])new Class[0]);
cachedValue$5aQdBH3R$551d7u2 = WebappController.class.getMethod("throwsException", (Class<?>[])new Class[0]);
cachedValue$5aQdBH3R$r5lbqa2 = WebappController.class.getMethod("createUser", String.class, String.class);
cachedValue$5aQdBH3R$pslu6e0 = WebappController.class.getMethod("deleteUser", String.class, String.class);
cachedValue$5aQdBH3R$tv4hlg2 = WebappController.class.getMethod("userList", (Class<?>[])new Class[0]);
cachedValue$5aQdBH3R$fe38712 = WebappController.class.getMethod("getUser", Long.TYPE);
cachedValue$5aQdBH3R$moqjd11 = WebappController.class.getDeclaredMethod("caughtException", (Class<?>[])new Class[0]);
log = LoggerFactory.getLogger((Class)WebappController.class);
}
public void setSkyWalkingDynamicField(final Object $EnhancedClassField_ws) {
this._$EnhancedClassField_ws = $EnhancedClassField_ws;
}
public Object getSkyWalkingDynamicField() {
return this._$EnhancedClassField_ws;
}
}
```
</details>
This is the same class after calling `Instrumentation.retransformClasses()`:
<details>
<summary>Decompiled source code</summary>
```java
package spp.example.webapp.controller;
import spp.example.webapp.service.*;
import org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.*;
import java.lang.reflect.*;
import spp.example.webapp.model.*;
import java.util.concurrent.*;
import org.springframework.web.bind.annotation.*;
import org.springframework.http.*;
import org.apache.skywalking.apm.toolkit.trace.*;
import org.slf4j.*;
@RestController
public class WebappController implements EnhancedInstance
{
private static final Logger log;
private final UserService userService = userService;
private volatile Object _$EnhancedClassField_ws;
public static volatile /* synthetic */ InstMethodsInter delegate$4vkd9v0;
public static volatile /* synthetic */ InstMethodsInter delegate$memmhe1;
public static volatile /* synthetic */ ConstructorInter delegate$20v8b80;
private static final /* synthetic */ Method cachedValue$5e7WjZyN$tcgf6s2;
private static final /* synthetic */ Method cachedValue$5e7WjZyN$551d7u2;
private static final /* synthetic */ Method cachedValue$5e7WjZyN$r5lbqa2;
private static final /* synthetic */ Method cachedValue$5e7WjZyN$pslu6e0;
private static final /* synthetic */ Method cachedValue$5e7WjZyN$tv4hlg2;
private static final /* synthetic */ Method cachedValue$5e7WjZyN$fe38712;
private static final /* synthetic */ Method cachedValue$5e7WjZyN$moqjd11;
public WebappController(final UserService userService) {
this(userService, null);
WebappController.delegate$20v8b80.intercept((Object)this, new Object[] { userService });
}
@RequestMapping(value = { "/users" }, method = { RequestMethod.GET })
public ResponseEntity<Iterable<User>> userList() {
return (ResponseEntity<Iterable<User>>)WebappController.delegate$memmhe1.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$nPDeHsP4(this), WebappController.cachedValue$5e7WjZyN$tv4hlg2);
}
@RequestMapping(value = { "/users/{id}" }, method = { RequestMethod.GET })
public ResponseEntity<User> getUser(@PathVariable final long id) {
return (ResponseEntity<User>)WebappController.delegate$memmhe1.intercept((Object)this, new Object[] { id }, (Callable)new WebappController$auxiliary$cByl7fIX(this, id), WebappController.cachedValue$5e7WjZyN$fe38712);
}
@RequestMapping(value = { "/users" }, method = { RequestMethod.POST })
public ResponseEntity<User> createUser(@RequestParam final String firstName, @RequestParam final String lastName) {
return (ResponseEntity<User>)WebappController.delegate$memmhe1.intercept((Object)this, new Object[] { firstName, lastName }, (Callable)new WebappController$auxiliary$sJY8TJLs(this, firstName, lastName), WebappController.cachedValue$5e7WjZyN$r5lbqa2);
}
@RequestMapping(value = { "/users" }, method = { RequestMethod.DELETE })
public void deleteUser(@RequestParam final String firstName, @RequestParam final String lastName) {
WebappController.delegate$memmhe1.intercept((Object)this, new Object[] { firstName, lastName }, (Callable)new WebappController$auxiliary$HdooN252(this, firstName, lastName), WebappController.cachedValue$5e7WjZyN$pslu6e0);
}
@RequestMapping(value = { "/throws-exception" }, method = { RequestMethod.GET })
public void throwsException() {
WebappController.delegate$memmhe1.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$vZfbpnR9(this), WebappController.cachedValue$5e7WjZyN$551d7u2);
}
@Trace
private void caughtException() {
WebappController.delegate$4vkd9v0.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$P2tJxjm1(this), WebappController.cachedValue$5e7WjZyN$moqjd11);
}
@Trace
private void uncaughtException() {
WebappController.delegate$4vkd9v0.intercept((Object)this, new Object[0], (Callable)new WebappController$auxiliary$7xenKkaR(this), WebappController.cachedValue$5e7WjZyN$tcgf6s2);
}
static {
ClassLoader.getSystemClassLoader().loadClass("org.apache.skywalking.apm.dependencies.net.bytebuddy.dynamic.Nexus").getMethod("initialize", Class.class, Integer.TYPE).invoke(null, WebappController.class, 433866945);
cachedValue$5e7WjZyN$tcgf6s2 = WebappController.class.getDeclaredMethod("uncaughtException", (Class<?>[])new Class[0]);
cachedValue$5e7WjZyN$551d7u2 = WebappController.class.getMethod("throwsException", (Class<?>[])new Class[0]);
cachedValue$5e7WjZyN$r5lbqa2 = WebappController.class.getMethod("createUser", String.class, String.class);
cachedValue$5e7WjZyN$pslu6e0 = WebappController.class.getMethod("deleteUser", String.class, String.class);
cachedValue$5e7WjZyN$tv4hlg2 = WebappController.class.getMethod("userList", (Class<?>[])new Class[0]);
cachedValue$5e7WjZyN$fe38712 = WebappController.class.getMethod("getUser", Long.TYPE);
cachedValue$5e7WjZyN$moqjd11 = WebappController.class.getDeclaredMethod("caughtException", (Class<?>[])new Class[0]);
log = LoggerFactory.getLogger((Class)WebappController.class);
}
}
```
</details>
----
The primary difference between the two is that fields like `cachedValue$5aQdBH3R$551d7u2` have been renamed and the second file is missing the necessary `setSkyWalkingDynamicField/getSkyWalkingDynamicField` methods.
The latter issue seems easy to solve as you could simply check the trace stack for `Instrumentation.retransformClasses()` and allow the enhancement to occur again. The former issue seems like it might be a bit harder and I'm curious if anyone has an idea how to solve it. The ways I've been thinking about solving it are either to:
- generate unique but consistent fields names (so each time it comes up with the same field names as before)
- save an additional map to each class which specificies what the existing fields are and reuse the previous names
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[GitHub] [skywalking] BFergerson commented on issue #6701: Redefinition support
Posted by GitBox <gi...@apache.org>.
BFergerson commented on issue #6701:
URL: https://github.com/apache/skywalking/issues/6701#issuecomment-814911373
Thank you @wu-sheng, this is exactly what I need.
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[GitHub] [skywalking] wu-sheng commented on issue #6701: Redefinition support
Posted by GitBox <gi...@apache.org>.
wu-sheng commented on issue #6701:
URL: https://github.com/apache/skywalking/issues/6701#issuecomment-814734300
Hi, we used to face retransferring issues, but by another agent not inside the agent core.
Could you try `agent.is_cache_enhanced_class` and `agent.class_cache_mode` on the agent.config? The reference doc is https://skywalking.apache.org/docs/main/latest/en/setup/service-agent/java-agent/readme/
This config should be able to cache the transferred source codes to avoid retransferring changes, which seems the case your described.
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[GitHub] [skywalking] BFergerson closed issue #6701: Redefinition support
Posted by GitBox <gi...@apache.org>.
BFergerson closed issue #6701:
URL: https://github.com/apache/skywalking/issues/6701
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