International Business Machines Corporation

IBM Canada Limited - IBM Canada Limitee

Daniel J Heidinga

Graham Alan Chapman

Oluwatobi Ajila

Vijay Sundaresan

Andrew James Craik

Michael H Dawson

Karl Michael Taylor

Charles Robert Gracie

Sharon Wang

Mark Graham Stoodley

Aleksandar Micic

Patrick R Doyle

Peter Duncan Shipton

Kenneth Blair Kent

Hang Shao

Bjoern Vaardal

David D Bremner

Shijie Xu

Devarghya Bhattacharya

Jinghua Feng

Peter Wiebe Burka

Andrew Russell Low

Angela Lin

Marius Pirvu

Irwin D'Souza

Ashutosh Mehra

Kevin James Langman

Nicholas James Coughlin

Babneet Singh

Olivier P Thomann

Parker Lees

Anyang Yu

Dhruv Chopra

Alen Badel

Zi Jian Lin

Gordon Duzhou

James I Gartley

Daihee Kim

James Ian Andrew Gartley

Peter W Burka

Karl M Taylor

Olivier Thomann

A computer-implemented method for bytecode class verification includes: encountering a class requiring verification of its bytecode during a run of an application; determining whether class relationship data for the class exists in a shared classes cache; in response to a determination that the class relationship data for the class does not exist in the shared classes cache: performing a linear bytecode walk of the bytecode to identify relationship data for the class and verify that the bytecode is well-formed; and storing the identified relationship data as the class relationship data for the class in the shared classes cache; in response to a determination that the class relationship data for the class does exist in the shared classes cache: retrieving the class relationship data for the class from the shared classes cache; and processing the class relationship data.

Bytecode verification using class relationship caching

A snapshot handler is registered with an event monitoring subsystem of a process virtual machine, the registering specifying a trigger event of the snapshot handler, wherein the trigger event comprises execution of a specified portion of an application executing in the process virtual machine, the trigger event specified externally from a source code of the application. Responsive to the event monitoring subsystem detecting an occurrence of the trigger event, the snapshot handler is executed, storing data of an execution state of the process virtual machine at a time of occurrence of the trigger event.

Performing an application snapshot using process virtual machine resources

An embodiment includes requesting, by a compiler responsive to execution of a first code segment, a first profile dataset associated with the first code segment. The embodiment also includes executing, responsive to receiving an indication that the first profile dataset is not available, a querying process that searches other code segments based on specified criteria relating to an attribute of the first code segment. The embodiment also includes receiving a search result from the querying process, where the search result includes a second code segment. The embodiment also includes generating an extrapolated profile dataset based at least in part on the second code segment. The embodiment stores the extrapolated profile dataset in memory associated with the first code segment, and the compiler performs an optimization process on the first code segment using the extrapolated profile dataset.

Deriving profile data for compiler optimization

Resolving segmented constant pools in a virtual machine managed runtime. An embodiment includes allocating, using one or more processors of a computing device, for each specialization created in a class of specializations, a constant pool (CP) cache, assigning an owner to each segment of constant pools, maintaining, in a memory of the computing device, a list of specializations in the class, and copying, upon determining that a CP segment entry visible to the specialization is resolved in the owner, the entry to a specializations cache of the memory. An embodiment includes assigning a new specialized CP segment as an owner of that CP segment and adding a new entry associated with the new specialization to a template class owners table, retrieving, based on looking for entry at runtime, a slot pointed to in the owners table and resolving the CP entry in the constant pool cache of the owner.

Resolution of segmented constant pools

A method list is built for a currently executing application within a process virtual machine at a snapshot point, the method list comprising a set of methods capable of being executed by the currently executing application after the snapshot point, the snapshot point comprising an execution state of the currently executing application when a snapshot process is triggered. Profiling data of the currently executing application, collected prior to reaching the snapshot point, is committed, to a designated storage location. Using the profiling data and a just-in-time compiler of the process virtual machine, a method in the method list is compiled. Snapshot data comprising data of the execution state of the currently executing application at the snapshot point, including a result of the compiling, is stored.

Compilation strategy for a sharable application snapshot

An embodiment includes executing a code interpretation engine such that the interpretation engine interprets a first portion of a source code that includes a first comparison between a first pair of operands. The embodiment also includes performing, in memory, a first bitwise comparison between a block Aand a block Bof the first portion of the source code. The embodiment also speeds up execution of the first portion of the source code responsive to the first bitwise comparison producing a negative result. The embodiment speeds up the first portion by omitting at least one of (i) a second bitwise comparison between a block Aand a block B, and (ii) a field-wise comparison between a block Aand a block B

Performance optimization of class instance comparisons

Embodiments of the present invention comprise a class sharing orchestrator (CSO) operating as a subsystem of a container orchestrator. The CSO manages sharing of class data among containerized applications to improve startup performance, CPU consumption and memory footprint. The CSO stores application class data in a shared class cache (SCC). The CSO provides a compatible SCC to every deployed application running within the CSO's purview. The CSO collects SCC data from running applications, and processes the data offline to continuously improve the quality of SCCs provided to each deployment, while causing minimum impact to running applications. The CSO combines updates from running applications of a given type to generate an improved quality SCC for use by newly launched applications of the same type. The CSO comprises an SCC update mechanism that optimizes the size, and network traffic, associated with SCC data exchange, and guarantees SCC quality improves over time.

Sharing cached class data in a containerized environment

Optimizing containerized applications includes receiving managed runtime code, creating a first container within a managed runtime environment, and executing the managed runtime code in the first container within the managed runtime environment. Responsive to a determination that the managed runtime environment has performed at least one optimization of the managed runtime code to create optimized managed runtime code during a first lifetime of the managed runtime environment, the first container is checkpointed into a first memory image to create a first checkpointed container including the optimized managed runtime code. The first checkpointed container is stored.

Checkpointing and restoring containers to optimize containerized managed runtime applications

During verification of a bytecode, when a second class remains to be loaded for verification in an MRE, a verifier in the MRE is prevented from loading the second class, where the bytecode includes a relationship between a first class and the second class. The relationship is recorded and the verifier is caused to omit a loading operation on the second class. An execution is started of an application encoded in the bytecode. The second class is caused to be loaded and verified prior to a use of the second class during the execution.

Deferred bytecode class verification in managed runtime environments

A computerized operating system begins a garbage-collection operation by collecting a set of 'garbage' data objects to be deleted. Certain of these objects are identified, either by an embedded identifier or by an entry in a sensitive-objects data structure, as containing sensitive data. When the garbage collector moves or deletes a sensitive object during the garbage-collection procedure, the collector zeroes out any residual data left at the object's original location in memory or secondary storage. If the collector determines that the object no longer has any connection to other software entities, the collector zeroes out the storage locations of all identified instances of the object. The collector then updates the data structure to indicate the current location of sensitive objects that have been moved or copied, and deletes entries for zeroed out instances of deleted sensitive objects.

Operating system garbage-collection with integrated clearing of sensitive data

A method of maintaining correctness of pointers from a managed heap to off-heap memory includes storing in a cache a first heap object in a managed heap that holds at least one off-heap pointer pointing to a first off-heap data structure and creating a weak reference node linked to the first heap object such that the first heap object is not kept alive by the weak reference node during garbage collection. Further disclosed are systems for maintaining correctness of pointers from a managed heap to off-heap memory.

Maintaining correctness of pointers from a managed heap to off-heap memory

Systems and methods for selective stack trace generation during Java exception handling are disclosed. In embodiments, a method includes determining, by a Java virtual machine (JVM) of a computing device, that an exception object escapes a catch block of Java bytecodes; setting, by the JVM of the computing device, an escaped flag based on the determining that the exception object escapes the catch block; walking, by the JVM of the computing device, a call stack to locate an applicable catch block for the exception object, wherein the applicable catch block is the catch block; determining, by the JVM of the computing device, that the escaped flag is set in response to locating the applicable catch block; and creating, by the JVM of the computing device, a stack trace based on the determining that the escaped flag is set.

Selective stack trace generation during java exception handling

A computer-implemented method includes: selecting, by a computer device, a set of fields in a program which are marked as final fields to be treated as constants; adding, by the computer device, detection logic to the program, the detection logic including a process that detects writes to the final fields to be treated as constants; compiling, by the computer device, the program into compiled code; executing, by the computer device, the compiled code; detecting, by the computer device, a write to a first one of the final fields to be treated as constants; and transitioning, by the computer device, execution of the compiled code from the compiled code to an interpreter for processing by compensation code that operates on the first one of the final fields to be treated as constants.

Compile-time folding of assumed constant values

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Daniel J Heidinga