8193818 : Remove unused single_step field from java.lang.Thread

[Lance Andersen]

+1
> On Feb 15, 2018, at 6:42 AM, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> 
> On 19/12/2017 11:06, Alan Bateman wrote:
>> I've been going through the fields in java.lang.Thread and I'm wondering if this field can be removed:
>> 
>>     /* Whether or not to single_step this thread. */
>>     private boolean     single_step;
>> 
>> This field was used in the original Classic VM (pre-OpenJDK history). It doesn't appear to be used in the HotSpot VM.
>> 
>> Does anyone know of any reason to keep it? Are there other VMs using it by any chance?
> No one screamed so I'd like to go ahead and remove this field. I've created JDK-8193818 to track it, the change (below) is trivial.
> 
> -Alan
> 
> 
> --- a/src/java.base/share/classes/java/lang/Thread.java
> +++ b/src/java.base/share/classes/java/lang/Thread.java
> @@ -1,5 +1,5 @@
>  /*
> - * Copyright (c) 1994, 2017, Oracle and/or its affiliates. All rights reserved.
> + * Copyright (c) 1994, 2018, Oracle and/or its affiliates. All rights reserved.
>   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
>   *
>   * This code is free software; you can redistribute it and/or modify it
> @@ -150,9 +150,6 @@
>      private Thread         threadQ;
>      private long           eetop;
> 
> -    /* Whether or not to single_step this thread. */
> -    private boolean     single_step;
> -
>      /* Whether or not the thread is a daemon thread. */
>      private boolean     daemon = false;

 <http://oracle.com/us/design/oracle-email-sig-198324.gif>
 <http://oracle.com/us/design/oracle-email-sig-198324.gif> <http://oracle.com/us/design/oracle-email-sig-198324.gif>
 <http://oracle.com/us/design/oracle-email-sig-198324.gif>Lance Andersen| Principal Member of Technical Staff | +1.781.442.2037
Oracle Java Engineering 
1 Network Drive 
Burlington, MA 01803
Lance.Andersen at oracle.com <mailto:Lance.Andersen at oracle.com>