[HTTPCLIENT-2125] NullPointerException in BasicHttpClientConnectionManager

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.0.3
• Fix Version/s: 5.0.4, 5.1-beta1
• Component/s: HttpClient (classic)
• Assignee: Unassigned
• Reporter: Dominik Derwiński
• Created: 02/Nov/20 15:38
• Updated: 11/Feb/21 17:53
• Resolved: 02/Nov/20 15:48

Description

After switching to HttpClient 5 I get a NPE in a code that was previously working. It's a pretty simple line

try (CloseableHttpResponse response = httpclient.execute(get, context)) {

which causes this:

Caused by: java.lang.NullPointerException
	at org.apache.hc.client5.http.impl.io.BasicHttpClientConnectionManager.release(BasicHttpClientConnectionManager.java:278)
	at org.apache.hc.client5.http.impl.classic.InternalExecRuntime.discardEndpoint(InternalExecRuntime.java:245)
	at org.apache.hc.client5.http.impl.classic.InternalExecRuntime.releaseEndpoint(InternalExecRuntime.java:259)
	at org.apache.hc.client5.http.impl.classic.MainClientExec.execute(MainClientExec.java:136)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement.execute(ExecChainElement.java:51)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement$1.proceed(ExecChainElement.java:57)
	at org.apache.hc.client5.http.impl.classic.ConnectExec.execute(ConnectExec.java:181)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement.execute(ExecChainElement.java:51)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement$1.proceed(ExecChainElement.java:57)
	at org.apache.hc.client5.http.impl.classic.ProtocolExec.execute(ProtocolExec.java:172)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement.execute(ExecChainElement.java:51)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement$1.proceed(ExecChainElement.java:57)
	at org.apache.hc.client5.http.impl.classic.HttpRequestRetryExec.execute(HttpRequestRetryExec.java:93)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement.execute(ExecChainElement.java:51)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement$1.proceed(ExecChainElement.java:57)
	at org.apache.hc.client5.http.impl.classic.ContentCompressionExec.execute(ContentCompressionExec.java:128)
	at org.apache.hc.client5.http.impl.classic.ExecChainElement.execute(ExecChainElement.java:51)
	at org.apache.hc.client5.http.impl.classic.InternalHttpClient.doExecute(InternalHttpClient.java:178)
	at org.apache.hc.client5.http.impl.classic.CloseableHttpClient.execute(CloseableHttpClient.java:75)

The request itself seems to be working, the problem is closing connection (I'm using a NoConnectionReuseStrategy which mimics the old Strategy available in version 4). This is in the log before crash:

[2020-11-02 16:35:53.389] [org.apache.hc.client5.http.impl.io.DefaultManagedHttpClientConnection] [main] [DEBUG] [org.apache.hc.client5.http.impl.io.DefaultManagedHttpClientConnection] [close] [143] : http-outgoing-0: close connection IMMEDIATE
[2020-11-02 16:35:53.390] [org.apache.hc.client5.http.impl.classic.InternalHttpClient] [main] [DEBUG] [org.apache.hc.client5.http.impl.classic.InternalExecRuntime] [discardEndpoint] [239] : InternalConnectionEndpoint-5175d9ad: endpoint closed
[2020-11-02 16:35:53.390] [org.apache.hc.client5.http.impl.classic.InternalHttpClient] [main] [DEBUG] [org.apache.hc.client5.http.impl.classic.InternalExecRuntime] [discardEndpoint] [243] : InternalConnectionEndpoint-5175d9ad: discarding endpoint
[2020-11-02 16:35:53.390] [org.apache.hc.client5.http.impl.io.BasicHttpClientConnectionManager] [main] [DEBUG] [org.apache.hc.client5.http.impl.io.BasicHttpClientConnectionManager] [closeConnection] [209] : Closing connection GRACEFUL

Seems like the code doesn't check whether conn is null when calling conn.passivate(); (but it does check for null when doing debug logging at start of release method).