The following test failed in the JDK16 CI:

applications/kitchensink/Kitchensink.java

Here's a snippet from the log file:

Iteration start: Allocator at Thu Dec 24 05:08:04 GMT 2020


The tail of stress stdout is:
For random generator using seed: 4568891173695790174
To re-run test with same seed value please add "-Djdk.test.lib.random.seed=4568891173695790174" to command line.
Stress process main method is started.
[thread 29496 also had an error]
#
# A fatal error has been detected by the Java Runtime Environment:
#
# EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0000023843d80fe1, pid=37324, tid=52544
#
# JRE version: Java(TM) SE Runtime Environment (16.0+30) (build 16-ea+30-2128)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (16-ea+30-2128, mixed mode, sharing, tiered, g1 gc, windows-amd64)
# Problematic frame:
# C 0x0000023843d80fe1
#
# Core dump will be written. Default location: T:\\testoutput\\test-support\\jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink_java\\scratch\\0\\hs_err_pid37324.mdmp
#
# JFR recording file will be written. Location: T:\\testoutput\\test-support\\jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink_java\\scratch\\0\\hs_err_pid37324.jfr
#
Unsupported internal testing APIs have been used.

# An error report file with more information is saved as:
# T:\\testoutput\\test-support\\jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink_java\\scratch\\0\\hs_err_pid37324.log
[thread 45052 also had an error]

[error occurred during error reporting (), id 0xc0000005, EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00007ffcbd9519ff]

#
# If you would like to submit a bug report, please visit:
# https://bugreport.java.com/bugreport/crash.jsp
#
----------System.err:(232/18984)*----------

Here's snippets from the hs_err_pid file:

--------------- T H R E A D ---------------

Current thread (0x0000023e611925c0): JavaThread "Thread-2698" [_thread_in_Java, id=52544, stack(0x0000009b05f00000,0x0000009b06000000)]

Stack: [0x0000009b05f00000,0x0000009b06000000], sp=0x0000009b05ffeb70, free space=1018k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C 0x0000023843d80fe1

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)

[error occurred during error reporting (printing Java stack), id 0xc0000005, EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00007ffcbd9519ff]


siginfo: EXCEPTION_ACCESS_VIOLATION (0xc0000005), data execution prevention violation at address 0x0000023843d80fe1


Register to memory mapping:

RIP=0x0000023843d80fe1 points into unknown readable memory: 00 00 00 00 00 00 00
RAX=0x0000000005ffeb98 is an unknown value
RBX=0x00000000000000b0 is an unknown value
RCX=0x0000023e611925c0 is a thread
RDX=0x000000000000000b is an unknown value
RSP=0x0000009b05ffeb70 is pointing into the stack for thread: 0x0000023e611925c0
RBP=0x0000009b05ffebe0 is pointing into the stack for thread: 0x0000023e611925c0
RSI=0x0000023e63a63f40 points into unknown readable memory: 0x00000000000003d8 | d8 03 00 00 00 00 00 00
RDI=0x0000023e5edcbf30 points into unknown readable memory: 0x0000007000000100 | 00 01 00 00 70 00 00 00
R8 =0x00000238049148c0 points into unknown readable memory: 0x0000023804910e70 | 70 0e 91 04 38 02 00 00
R9 =0x0000023dd8cd9ad0 is an oop: java.util.TreeMap$Entry
{0x0000023dd8cd9ad0} - klass: 'java/util/TreeMap$Entry'
R10=0x00007ffcbe18cec0 jvm.dll
R11=0x0000009b05ffe030 is pointing into the stack for thread: 0x0000023e611925c0
R12=0x0000000000000003 is an unknown value
R13=0x0000000800944442 is pointing into metadata
R14=0x0000009b05ffec00 is pointing into the stack for thread: 0x0000023e611925c0
R15=0x0000023e611925c0 is a thread


Registers:
RAX=0x0000000005ffeb98, RBX=0x00000000000000b0, RCX=0x0000023e611925c0, RDX=0x000000000000000b
RSP=0x0000009b05ffeb70, RBP=0x0000009b05ffebe0, RSI=0x0000023e63a63f40, RDI=0x0000023e5edcbf30
R8 =0x00000238049148c0, R9 =0x0000023dd8cd9ad0, R10=0x00007ffcbe18cec0, R11=0x0000009b05ffe030
R12=0x0000000000000003, R13=0x0000000800944442, R14=0x0000009b05ffec00, R15=0x0000023e611925c0
RIP=0x0000023843d80fe1, EFLAGS=0x0000000000010246

This failure reminds of the following bug:

    JDK-8258646 Kitchensink.java crashed in JavaThread "AllocatorStressModule"

except that the crash did not happen in the AllocatorStressModule".
According to the log file:

Iteration start: Allocator at Thu Dec 24 05:08:04 GMT 2020

an AllocatorStressModule run started just before the crash
so this might be related to JDK-8258646.