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ConcurrentModificationException in AbstractRequestExpectationManager [SPR-15029] #19596

spring-issuemaster opened this issue Dec 19, 2016 · 2 comments


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commented Dec 19, 2016

Alastair Paterson opened SPR-15029 and commented

We are using MockRestServiceServer in conjunction with expectations to conduct testing of our Spring application.

We have noticed that when a method under test invokes asynchronous network requests the MockRestServiceServer will occasionally throw a ConcurrentModificationException causing the test to fail. The issue is observed when using parallelStream() as well as other asynchronous methods. Reintroducing concurrency alleviates the issue.

Please find attached a trivial Spring Boot application that reproduces this issue.

Affects: 4.2.4, 4.3.4


Referenced from: commits fcead67, 6e508f7


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commented Jan 3, 2017

Rossen Stoyanchev commented

Stack trace from given example:

Caused by: java.util.ConcurrentModificationException
	at java.util.LinkedHashMap$LinkedHashIterator.nextNode(
	at java.util.LinkedHashMap$
	at org.springframework.test.web.client.AbstractRequestExpectationManager$RequestExpectationGroup.findExpectation(
	at org.springframework.test.web.client.UnorderedRequestExpectationManager.validateRequestInternal(
	at org.springframework.test.web.client.AbstractRequestExpectationManager.validateRequest(
	at org.springframework.test.web.client.MockRestServiceServer$MockClientHttpRequestFactory$1.executeInternal(
	at org.springframework.mock.http.client.MockClientHttpRequest.execute(
	at org.springframework.web.client.RestTemplate.doExecute(
	at org.springframework.web.client.RestTemplate.execute(
	at org.springframework.web.client.RestTemplate.getForObject(

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commented Jan 17, 2017

Rossen Stoyanchev commented

This should be fixed. I ran the sample a few times and I don't see the error any more after the fix. Thanks for the report and sample!

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