Suppressed NPE in Json.encodeToString

[kosiakk]

Describe the bug

Java Exception breakpoint fires for NPE in JSON library ArrayPools.kt in the try-catch environment.
This has no other negative effects because the NPE is suppressed:

package kotlinx.serialization.json.internal

/*
 * Not really documented kill switch as a workaround for potential
 * (unlikely) problems with memory consumptions.
 */
private val MAX_CHARS_IN_POOL = runCatching {
    System.getProperty("kotlinx.serialization.json.pool.size").toIntOrNull()
}.getOrNull() ?: 2 * 1024 * 1024

In most cases the property is not set, it's not even documented. As result, Kotlin NullPointerException is on the main path for all JSON-write operations: getProperty("...").toIntOrNull()
I suggest we should not use the try-catch to handle the expected NPE, but instead use a null-safe call:

private val MAX_CHARS_IN_POOL = System.getProperty("kotlinx.serialization.json.pool.size")?.toIntOrNull() ?: 2 * 1024 * 1024

To Reproduce

Json { prettyPrint = true }.encodeToString("anything")

Expected behavior

No preventable NPE should be thrown.

Environment

• Kotlin version: 2.0.21
• Library version: 1.7.3
• Kotlin platforms: JVM

[shanshin]

Hi, thanks for the report!

Indeed, to improve readability the additional processing of the null should be added.

However, this exception does not have a significant impact on performance, because the value is initialized once, when the variable MAX_CHARS_IN_POOL is accessed for the first time.
You can verify this if you refer to the stacktrace, in which runCatching is called from the <clinit> of class ArrayPoolsKt, which is executed once when loading the class into the JVM.