Marea: An Efficient Application-Level Object Graph Swapper.

Abstract

During the execution of object-oriented applications, several millions of objects are created, used and then collected if they are not referenced. Problems appear when objects are unused but cannot be garbage-collected because they are still referenced from other objects. This is an issue because those objects waste primary memory and applications use more primary memory than they actually need. We claim that relying on the operating system's (OS) virtual memory is not always enough since it cannot take into account the domain and structure of applications. At the same time, applications have no easy way to parametrize nor cooperate with memory management. In this paper, we present Marea, an efficient application-level object graph swapper for object-oriented programming languages. Its main goal is to offer the programmer a novel solution to handle application-level memory. Developers can instruct our system to release primary memory by swapping out unused yet referenced objects to secondary memory. Our approach has been qualitatively and quantitatively validated. Our experiments and benchmarks on real-world applications show that Marea can reduce the memory footprint between 23% and 36%.

Improving live debugging of concurrent threads through thread histories

“…From the selected languages we derived a list of debuggers by including the standard debugger for each language (if one exists) and possibly others that are used by a significant number of developers (e.g., debuggers used by popular development environments). The debuggers covered by our survey are: Java Debugger Interface 13 (Java), Visual Studio debugger 14 (C # , C ++ , Visual Basic .NET, JavaScript), PyDev 15 (Python), pdb 16 (Python), perldebug 17 (Perl), GDB 18 (C), Chrome development tools 19 (JavaScript), XDebug 20 (PHP), Zend Debugger 21 (PHP), debug.rb 22 (Ruby), LLDB 23 (Objective-C, Swift), GHCi debugger (Haskell) 24 , Concurrent Haskell debugger [6] (Haskell), SISC debugger 25 (Scheme), Scala asynchronous debugger 26 (Scala), Self debugger 27 (Self), ocamldebug 28 (OCaml), XPCE debugger 29 (Prolog), Pharo debugger. 30…”

“…The additional time required for compression on the other hand may have a negative impact on performance, so that moving the stack copy procedure into the virtual machine may indeed become necessary. A similar alternative is to use Marea [23], a library that can be used to write graphs of objects to secondary memory and reload them on demand. Another option might be to reclaim memory from copied call stacks when necessary, starting with the oldest copies.…”