Garbage collection stops after exception in SoapClient

Description

The following code:

<?php

class A
{
	public $b;
}

class B
{
	public $a;
}

function buildCycle()
{
	$a = new A();
	$b = new B();
	$a->b = $b;
	$b->a = $a;
}

function failySoapCall()
{

	try {
		new SoapClient('https://nowhere.inexistent.space/?WSDL');
	}
	catch (Exception) {
		echo "Soap call failed\n";
	}
}

function gc()
{
	gc_collect_cycles();
	echo "GC Runs: " . gc_status()['runs'] . "\n";
}


buildCycle();
gc();
buildCycle();
gc();
buildCycle();
gc();

failySoapCall();

buildCycle();
gc();
buildCycle();
gc();
buildCycle();
gc();

Resulted in this output:

GC Runs: 1
GC Runs: 2
GC Runs: 3
Soap call failed
GC Runs: 3
GC Runs: 3
GC Runs: 3

But I expected this output instead:

GC Runs: 1
GC Runs: 2
GC Runs: 3
Soap call failed
GC Runs: 4
GC Runs: 5
GC Runs: 6

The SOAP exception apparently stops the garbage collector. I experienced this problem with a large, long running process. Its memory usage is intensive but stable. Until it encounters a SOAP exception: its memory usage skyrockets, and gc_status() reports that no more gc run is done.

PHP Version

PHP 8.1.13

Operating System

Alpine 3.16

Run the provided PHP reproduction with SoapClient, gc_collect_cycles(), and gc_status() on PHP 8.1.13 and Alpine 3.16. Start by tracing the exception path and its interaction with cyclic garbage collection. Done means garbage-collection runs continue after the failed SOAP call and the reported cycle counts match the expected output.