yew1eb commented on issue #1602:
URL: https://github.com/apache/auron/issues/1602#issuecomment-3510960356
I reproduced the failure by loading the class in a test and catch the
exception stack:
```
try {
Class.forName("org.apache.spark.sql.auron.NativeConverters$");
} catch (Throwable t) {
t.printStackTrace();
}
```
Result:
```
java.lang.ExceptionInInitializerError
Caused by: java.lang.NullPointerException
at
org.apache.spark.sql.auron.NativeConverters$.<init>(NativeConverters.scala:91)
at
org.apache.spark.sql.auron.NativeConverters$.<clinit>(NativeConverters.scala)
```
Line 91 in `NativeConverters.scala`:
```
AuronAdaptor.getInstance.getAuronConfiguration
```
**Root cause:**
The `NoClassDefFoundError` is just a symptom -- the real issue is an NPE
because `AuronAdaptor.INSTANCE` is `null` on `Executor`. Initialization of
`INSTANCE` depends on `Shims.get` (a lazy val). If `Shims.get` is not invoked
early in the `Executor`, `AuronAdaptor.getInstance()` returns `null`,
triggering the `NPE` during static initialization of `NativeConverters$`.
**Proposed fix:**
Make `AuronAdaptor.getInstance()` self-initializing with double-checked
locking and a unified default initializer:
```
public static AuronAdaptor getInstance() {
if (INSTANCE == null) {
synchronized (AuronAdaptor.class) {
if (INSTANCE == null) {
initializeDefault();
}
}
}
return INSTANCE;
}
public static synchronized void initializeDefault() {
if (INSTANCE == null) {
initInstance(new SparkAuronAdaptor());
}
}
```
And update Shims.scala to use the same entry point:
```
object Shims {
lazy val get: Shims = {
AuronAdaptor.initializeDefault()
...
}
```
This ensures consistent, automatic, thread-safe initialization from both
`Shims.get` and `AuronAdaptor.getInstance()`, eliminating the fragile ordering
dependency.
Happy to open a PR if this approach is approved.
@Tartarus0zm @richox any feedback ?
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