Documents to gather

When a crash takes place, diagnostic data is required to help diagnose the problem.

When one of these unrecoverable signals occurs, the JVM Signal Handler takes control. The default action of the signal handler is to produce a transaction dump (through the BCP IEATDUMP service), a JVM snap trace dump, and a formatted Javacore. Output is written to the message stream that is written to stderr in the form of:

Unhandled exception
Type=Segmentation error vmState=0x00000000
Target=2_30_20060227_05498_bHdSMr (z/OS 01.06.00)
CPU=s390 (2 logical CPUs) (0x180000000 RAM)
J9Generic_Signal_Number=00000004 Signal_Number=0000000b Error_Value=00000000 Signal_Code=00000035
Handler1=115F8590 Handler2=116AFC60
gpr0=00000064 gpr1=00000000 gpr2=117A3D70 gpr3=00000000
gpr4=114F5280 gpr5=117C0E28 gpr6=117A2A18 gpr7=9167B460
gpr8=0000007E gpr9=116AF5E8 gpr10=1146E21C gpr11=0000007E
gpr12=1102C7D0 gpr13=11520838 gpr14=115F8590 gpr15=00000000
psw0=078D0400 psw1=917A2A2A
fpr0=48441040 fpr1=3FFF1999 fpr2=4E800001 fpr3=99999999
fpr4=45F42400 fpr5=3FF00000 fpr6=00000000 fpr7=00000000
fpr8=00000000 fpr9=00000000 fpr10=00000000 fpr11=00000000
fpr12=00000000 fpr13=00000000 fpr14=00000000 fpr15=00000000
Program_Unit_Name=
Program_Unit_Address=1167B198 Entry_Name=j9sig_protect
Entry_Address=1167B198
JVMDUMP006I Processing Dump Event "gpf", detail "" - Please Wait.
JVMDUMP007I JVM Requesting System Dump using 'MYUSER.JVM.TDUMP.MYUSER1.D060309.T144842'
IEATDUMP in progress with options 
SDATA=(LPA,GRSQ,LSQA,NUC,PSA,RGN,SQA,SUM,SWA,TRT) IEATDUMP success for 
DSN='MYUSER.JVM.TDUMP.MYUSER1.D060309.T144842' JVMDUMP010I System Dump written 
to MYUSER.JVM.TDUMP.MYUSER1.D060309.T144842 JVMDUMP007I JVM Requesting Snap 
Dump using '/u/myuser/mydir/Snap0001.20060309.144842.196780.trc' JVMDUMP010I 
Snap Dump written to /u/myuser/mydir/Snap0002.20060309.144842.196780.trc 
JVMDUMP007I JVM Requesting Java Dump using 
'/u/myuser/mydir/javacore.20060309.144842.196780.txt' JVMDUMP010I Java Dump 
written to /u/myuser/mydir/javacore.20060309.144842.196780.txt JVMDUMP013I 
Processed Dump Event "gpf", detail "".

The output shows the location in zfs into which the Javacore file was written and the name of the MVS data set to which the transaction dump is written. These locations are configurable and are described in in the J9 VM reference and in the OpenJ9 user documentation.

These documents provide the ability to determine the failing function, and therefore decide which product owns the failing code, be it the JVM, application JNI code, or native libraries acquired from another vendor (for example native JDBC drivers).

The JVM will display error messages if it is unable to produce the dumps. The IEATDUMP error return codes, RC=... and RSN=..., are included in the messages. For more information about these return codes, see the documentation for your version of z/OS. For example, z/OS MVS Authorized Assembler Services Reference.

This example shows the error messages displayed when there is insufficient disk space to write the IEATDUMP:

JVMDUMP007I JVM Requesting System dump using 'J9BUILD.JVM.TDUMP.SSHD1.D080326.T081447'
IEATDUMP in progress with options SDATA=(LPA,GRSQ,LSQA,NUC,PSA,RGN,SQA,SUM,SWA,TRT)
IEATDUMP failure for DSN='J9BUILD.JVM.TDUMP.SSHD1.D080326.T081447' RC=0x00000008 RSN=0x00000026 
JVMDUMP012E Error in System dump: J9BUILD.JVM.TDUMP.SSHD1.D080326.T081447

When an IEATDUMP fails, an error message is also written to the operator console. If the IEATDUMP fails because of the 2 GB IEATDUMP size limit, you can use a SLIP trap to trigger an SVC DUMP to ensure all the required diagnostics information is available. See Setting up dumps for more information.

For more information, see MustGather: Read first for - Runtimes for Java Technology.