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  • Java Refuses to Start - Could not reserve enough space for object heap

    - by Randyaa
    Background We have a pool of aproximately 20 linux blades. Some are running Suse, some are running Redhat. ALL share NAS space which contains the following 3 folders: /NAS/app/java - a symlink that points to an installation of a Java JDK. Currently version 1.5.0_10 /NAS/app/lib - a symlink that points to a version of our application. /NAS/data - directory where our output is written All our machines have 2 processors (hyperthreaded) with 4gb of physical memory and 4gb of swap space. We limit the number of 'jobs' each machine can process at a given time to 6 (this number likely needs to change, but that does not enter into the current problem so please ignore it for the time being). Some of our jobs set a Max Heap size of 512mb, some others reserve a Max Heap size of 2048mb. Again, we realize we could go over our available memory if 6 jobs started on the same machine with the heap size set to 2048, but to our knowledge this has not yet occurred. The Problem Once and a while a Job will fail immediately with the following message: Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. We used to chalk this up to too many jobs running at the same time on the same machine. The problem happened infrequently enough (MAYBE once a month) that we'd just restart it and everything would be fine. The problem has recently gotten much worse. All of our jobs which request a max heap size of 2048m fail immediately almost every time and need to get restarted several times before completing. We've gone out to individual machines and tried executing them manually with the same result. Debugging It turns out that the problem only exists for our SuSE boxes. The reason it has been happening more frequently is becuase we've been adding more machines, and the new ones are SuSE. 'cat /proc/version' on the SuSE boxes give us: Linux version 2.6.5-7.244-bigsmp (geeko@buildhost) (gcc version 3.3.3 (SuSE Linux)) #1 SMP Mon Dec 12 18:32:25 UTC 2005 'cat /proc/version' on the RedHat boxes give us: Linux version 2.4.21-32.0.1.ELsmp ([email protected]) (gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-52)) #1 SMP Tue May 17 17:52:23 EDT 2005 'uname -a' gives us the following on BOTH types of machines: UTC 2005 i686 i686 i386 GNU/Linux No jobs are running on the machine, and no other processes are utilizing much memory. All of the processes currently running might be using 100mb total. 'top' currently shows the following: Mem: 4146528k total, 3536360k used, 610168k free, 132136k buffers Swap: 4194288k total, 0k used, 4194288k free, 3283908k cached 'vmstat' currently shows the following: procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 610292 132136 3283908 0 0 0 2 26 15 0 0 100 0 If we kick off a job with the following command line (Max Heap of 1850mb) it starts fine: java/bin/java -Xmx1850M -cp helloworld.jar HelloWorld Hello World If we bump up the max heap size to 1875mb it fails: java/bin/java -Xmx1875M -cp helloworld.jar HelloWorld Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. It's quite clear that the memory currently being used is for Buffering/Caching and that's why so little is being displayed as 'free'. What isn't clear is why there is a magical 1850mb line where anything higher means Java can't start. Any explanations would be greatly appreciated.

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  • How to find number of memory accesses

    - by Sharat Chandra
    Can anybody tell me a unix command that can be used to find the number of memory accesses that took place in a given interval. vmstat, top and sar only give the amount of physical memory space occupied/available .. But do not give the number of memory of accesses in a given interval

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  • Retrieve Heap memory size and its usage statistics etc...?

    - by AKN
    Lets say I open some application or process. Did some work with that. Now I closed it. Need to know whether this application caused any memory leak. i.e used up some heap memory and not cleared it properly. Can I get this statistics some how? I'm using Visual Studio (for development) under Windows OS. Even I would be interested in knowing this information for any 3rd party application.

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  • Memory Profiling: How to detect which application/package is consuming too much memory

    - by malvim
    Hi, I have a situation here at work where we run a JEE server with several applications deployed on it. Lately, we've been having frequent OutOfMemoryException's. We suspect some of the apps might be behaving badly, maybe leaking, or something. The problem is, we can't really tell which one. We have run some memory profilers (like YourKit), and they're pretty good at telling what classes use the most memory. But they don't show relationships between classes, so that leaves us with a situation like this: We see that there are, say, lots of Strings and int arrays and HashMap entries, but we can't really tell which application or package they come from. Is there a way of knowing where these objects come from, so we can try to pinpoint the packages (or apps) that are allocating the most memory? Thank you in advance.

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  • Memory leak - debugger and memory analyzer disagreeing

    - by Joe
    There is a memory leak in my android game - I've managed to narrow it down to a certain object, which has a list of objects to render on a texture. This object clears the list every time it draws though - so I can't work out how its managed to get thousands of elements in the list. I checked in the debugger and it doesn't have all these thousands of elements - usually about 2-20 which is what I'd expect... The game definitely slows down progressively only if I have rendering to texturing on. Here is a picture of Memory Analyzer showing 6,111 items: Memory Analyzer Here is a picture of the debugger showing 2: Debugger Can anyone help me find out whats wrong?

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  • find second smallest element in Fibonacci Heap

    - by Longeyes
    I need to describe an algorithm that finds the second smallest element in a Fibonacci-Heap using the Operations: Insert, ExtractMin, DecreaseKey and GetMin. The last one is an algorithm previously implemented to find and return the smallest element of the heap. I thought I'd start by extracting the minimum, which results in its children becoming roots. I could then use GetMin to find the second smallest element. But it seems to me that I'm overlooking other cases because I don't know when to use Insert and DecreaseKey, and the way the question is phrased seems to suggest I should need them.

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  • Memory dump much smaller than available memory

    - by Daniel
    I have a Tomcat Application Server that is configured to create a memory dump on OOM, and it is started with -Xmx1024M, so a Gigabyte should be available to him. Now I found one such dump and it contains only 260MB of unretained memory. How is it possible that the dump is so much smaller than the size he should have available?

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  • what kind of memory can be categorized as Modified Memory in Resource Monitor

    - by Kavin
    In Windows 7 and Windows 2008 R2, there is a new Resource Monitor that is very useful and powerful to monitor the system. In the Memory section, I see a section called Modified (orange) The official description is: Memory whose contents must be to disk before it can be used for another purpose. But I am still confused. What kinds of memory is Modified? In which case can we say that this number of memory is Modified? Can anyone give me a specific example? Is the following guess correct? When a program want to write something into disk, it actually write the content to an IO buffer, which is in the memory. After OS flush this area of memory into disk, the memory is modified or standby?

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  • very large string in memory

    - by bushman
    Hi, I am writing a program for formatting 100s of MB String data (nearing a gig) into xml == And I am required to return it as a response to an HTTP (GET) request . I am using a StringWriter/XmlWriter to build an XML of the records in a loop and returning the stringWriter.ToString() during testing I saw a few --out of memory exceptions-- and quite clueless on how to find a solution? do you guys have any suggestions for a memory optimized delivery of the response? is there a memory efficient way of encoding the data? or maybe chunking the data -- I just can not think of how to return it without building the whole thing into one HUGE string object thanks

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  • Decreasing cached memory and increasing Free memory in RAM

    - by Greenhorn
    Hi, Im using windows 2007 server 64 bit OS, I've uploaded the snap shot of my task manager when minimum processes running It shows Total memory 8190 mb *Cached memory 4315 mb* Free 3402 mb So effectively I get only 3402 mb of total RAM usage My question here is more than half is used for cached memory is there any means I can decrease this cached memory inturn I can increase my free memory. I need to do this because my Application requires at least 5GB RAM and it crashed when run in this system. Please give me a solution for this Thanks in advance

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  • NSCFString Memory Leak

    - by Lakshmie
    Hello, I have been solving a lot of memory leaks but have been unsuccessful in solving this one. There are tons of NSCF memory leaks coming due to [NSCFString substringWithRange:]. I have been checking all the String allocations and have released all of them at appropriate places. The responsible library: Foundation. Has anyone encountered this problem before? Can anyone suggest me as how I should takle this issue? Thanks, Lakshmie

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  • SQL SERVER – Introduction to SQL Server 2014 In-Memory OLTP

    - by Pinal Dave
    In SQL Server 2014 Microsoft has introduced a new database engine component called In-Memory OLTP aka project “Hekaton” which is fully integrated into the SQL Server Database Engine. It is optimized for OLTP workloads accessing memory resident data. In-memory OLTP helps us create memory optimized tables which in turn offer significant performance improvement for our typical OLTP workload. The main objective of memory optimized table is to ensure that highly transactional tables could live in memory and remain in memory forever without even losing out a single record. The most significant part is that it still supports majority of our Transact-SQL statement. Transact-SQL stored procedures can be compiled to machine code for further performance improvements on memory-optimized tables. This engine is designed to ensure higher concurrency and minimal blocking. In-Memory OLTP alleviates the issue of locking, using a new type of multi-version optimistic concurrency control. It also substantially reduces waiting for log writes by generating far less log data and needing fewer log writes. Points to remember Memory-optimized tables refer to tables using the new data structures and key words added as part of In-Memory OLTP. Disk-based tables refer to your normal tables which we used to create in SQL Server since its inception. These tables use a fixed size 8 KB pages that need to be read from and written to disk as a unit. Natively compiled stored procedures refer to an object Type which is new and is supported by in-memory OLTP engine which convert it into machine code, which can further improve the data access performance for memory –optimized tables. Natively compiled stored procedures can only reference memory-optimized tables, they can’t be used to reference any disk –based table. Interpreted Transact-SQL stored procedures, which is what SQL Server has always used. Cross-container transactions refer to transactions that reference both memory-optimized tables and disk-based tables. Interop refers to interpreted Transact-SQL that references memory-optimized tables. Using In-Memory OLTP In-Memory OLTP engine has been available as part of SQL Server 2014 since June 2013 CTPs. Installation of In-Memory OLTP is part of the SQL Server setup application. The In-Memory OLTP components can only be installed with a 64-bit edition of SQL Server 2014 hence they are not available with 32-bit editions. Creating Databases Any database that will store memory-optimized tables must have a MEMORY_OPTIMIZED_DATA filegroup. This filegroup is specifically designed to store the checkpoint files needed by SQL Server to recover the memory-optimized tables, and although the syntax for creating the filegroup is almost the same as for creating a regular filestream filegroup, it must also specify the option CONTAINS MEMORY_OPTIMIZED_DATA. Here is an example of a CREATE DATABASE statement for a database that can support memory-optimized tables: CREATE DATABASE InMemoryDB ON PRIMARY(NAME = [InMemoryDB_data], FILENAME = 'D:\data\InMemoryDB_data.mdf', size=500MB), FILEGROUP [SampleDB_mod_fg] CONTAINS MEMORY_OPTIMIZED_DATA (NAME = [InMemoryDB_mod_dir], FILENAME = 'S:\data\InMemoryDB_mod_dir'), (NAME = [InMemoryDB_mod_dir], FILENAME = 'R:\data\InMemoryDB_mod_dir') LOG ON (name = [SampleDB_log], Filename='L:\log\InMemoryDB_log.ldf', size=500MB) COLLATE Latin1_General_100_BIN2; Above example code creates files on three different drives (D:  S: and R:) for the data files and in memory storage so if you would like to run this code kindly change the drive and folder locations as per your convenience. Also notice that binary collation was specified as Windows (non-SQL). BIN2 collation is the only collation support at this point for any indexes on memory optimized tables. It is also possible to add a MEMORY_OPTIMIZED_DATA file group to an existing database, use the below command to achieve the same. ALTER DATABASE AdventureWorks2012 ADD FILEGROUP hekaton_mod CONTAINS MEMORY_OPTIMIZED_DATA; GO ALTER DATABASE AdventureWorks2012 ADD FILE (NAME='hekaton_mod', FILENAME='S:\data\hekaton_mod') TO FILEGROUP hekaton_mod; GO Creating Tables There is no major syntactical difference between creating a disk based table or a memory –optimized table but yes there are a few restrictions and a few new essential extensions. Essentially any memory-optimized table should use the MEMORY_OPTIMIZED = ON clause as shown in the Create Table query example. DURABILITY clause (SCHEMA_AND_DATA or SCHEMA_ONLY) Memory-optimized table should always be defined with a DURABILITY value which can be either SCHEMA_AND_DATA or  SCHEMA_ONLY the former being the default. A memory-optimized table defined with DURABILITY=SCHEMA_ONLY will not persist the data to disk which means the data durability is compromised whereas DURABILITY= SCHEMA_AND_DATA ensures that data is also persisted along with the schema. Indexing Memory Optimized Table A memory-optimized table must always have an index for all tables created with DURABILITY= SCHEMA_AND_DATA and this can be achieved by declaring a PRIMARY KEY Constraint at the time of creating a table. The following example shows a PRIMARY KEY index created as a HASH index, for which a bucket count must also be specified. CREATE TABLE Mem_Table ( [Name] VARCHAR(32) NOT NULL PRIMARY KEY NONCLUSTERED HASH WITH (BUCKET_COUNT = 100000), [City] VARCHAR(32) NULL, [State_Province] VARCHAR(32) NULL, [LastModified] DATETIME NOT NULL, ) WITH (MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA); Now as you can see in the above query example we have used the clause MEMORY_OPTIMIZED = ON to make sure that it is considered as a memory optimized table and not just a normal table and also used the DURABILITY Clause= SCHEMA_AND_DATA which means it will persist data along with metadata and also you can notice this table has a PRIMARY KEY mentioned upfront which is also a mandatory clause for memory-optimized tables. We will talk more about HASH Indexes and BUCKET_COUNT in later articles on this topic which will be focusing more on Row and Index storage on Memory-Optimized tables. So stay tuned for that as well. Now as we covered the basics of Memory Optimized tables and understood the key things to remember while using memory optimized tables, let’s explore more using examples to understand the Performance gains using memory-optimized tables. I will be using the database which i created earlier in this article i.e. InMemoryDB in the below Demo Exercise. USE InMemoryDB GO -- Creating a disk based table CREATE TABLE dbo.Disktable ( Id INT IDENTITY, Name CHAR(40) ) GO CREATE NONCLUSTERED INDEX IX_ID ON dbo.Disktable (Id) GO -- Creating a memory optimized table with similar structure and DURABILITY = SCHEMA_AND_DATA CREATE TABLE dbo.Memorytable_durable ( Id INT NOT NULL PRIMARY KEY NONCLUSTERED Hash WITH (bucket_count =1000000), Name CHAR(40) ) WITH (MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA) GO -- Creating an another memory optimized table with similar structure but DURABILITY = SCHEMA_Only CREATE TABLE dbo.Memorytable_nondurable ( Id INT NOT NULL PRIMARY KEY NONCLUSTERED Hash WITH (bucket_count =1000000), Name CHAR(40) ) WITH (MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_only) GO -- Now insert 100000 records in dbo.Disktable and observe the Time Taken DECLARE @i_t bigint SET @i_t =1 WHILE @i_t<= 100000 BEGIN INSERT INTO dbo.Disktable(Name) VALUES('sachin' + CONVERT(VARCHAR,@i_t)) SET @i_t+=1 END -- Do the same inserts for Memory table dbo.Memorytable_durable and observe the Time Taken DECLARE @i_t bigint SET @i_t =1 WHILE @i_t<= 100000 BEGIN INSERT INTO dbo.Memorytable_durable VALUES(@i_t, 'sachin' + CONVERT(VARCHAR,@i_t)) SET @i_t+=1 END -- Now finally do the same inserts for Memory table dbo.Memorytable_nondurable and observe the Time Taken DECLARE @i_t bigint SET @i_t =1 WHILE @i_t<= 100000 BEGIN INSERT INTO dbo.Memorytable_nondurable VALUES(@i_t, 'sachin' + CONVERT(VARCHAR,@i_t)) SET @i_t+=1 END The above 3 Inserts took 1.20 minutes, 54 secs, and 2 secs respectively to insert 100000 records on my machine with 8 Gb RAM. This proves the point that memory-optimized tables can definitely help businesses achieve better performance for their highly transactional business table and memory- optimized tables with Durability SCHEMA_ONLY is even faster as it does not bother persisting its data to disk which makes it supremely fast. Koenig Solutions is one of the few organizations which offer IT training on SQL Server 2014 and all its updates. Now, I leave the decision on using memory_Optimized tables on you, I hope you like this article and it helped you understand  the fundamentals of IN-Memory OLTP . Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Koenig

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  • sizes of RAM, of virtual memory and of swap for 32-bit OS

    - by Tim
    If I understand correctly, a 32-bit OS (Ubuntu) can only address 4GiB memory, so RAM with size larger than 4Gib will only be used 4Gib of itself and the rest is a waste. I am now confused about this situation for RAM with similar one for virtual memory and for swap. with virtual memory being swap + RAM, if the size of the virtual memory exceeds 4Gib, will the exceeding part be a waste for the 32-bit OS? if I now have to choose the size for my swap partition, is it a factor to consider that the 32-bit OS can only address 4GiB memory? Does the size of swap have to be chosen with respect to the 4Gib addressible limitation? Will the swap exceeding 4GiB always be a waste? is virtual memory equal to RAM and swap? or can virtual memory use space on the hard drive outside the swap partition? Thanks and regards!

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  • Does scheduling recycling app pool in IIS7 help the server conserve memory better?

    - by user29266
    Hello, I have a VPS (IIS7 with Win 2008) It's got: 40 websites and a SQL Server 2008 powering them with only 2 Gigs of RAM. None of the sites are mission critical, they are all just demos. I often have ram issues on the server because each site has does caching and generally uses a lot of memory. Would it make sense to set the application pools to recycle every 3 hours? I'm sure this would free up any memory leaks or processes left "hanging" Are there any other tips on this? Thank you very much!, Aron

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  • Heap Dump Root Classes

    - by Adnan Memon
    We have production system going into infinite loop of full gc and memory drops form 8 gigs to like 1 MB in just 2 minutes. After taking heap dump it tells me there an is an array of java.lang.Object ([Ljava.lang.Object) with millions of java.lang.String objects having same String taking 99% of heap. But it doesn't tell me which class is referencing to this array so that I can fix it in the code. I took the heap dump using jmap tool on JDK 6 and used JProfiler, NetBeans, SAP Memory Analyzer and IBM Memory Analyzer but none of those tell me what is causing this huge array of objects?? ... like what class is referencing to it or contains it. Do I have to take a different dump with different config in order to get that info? ... Or anything else that can help me find out the culprit class causing this ... it will help a lot.

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  • Loads of memory in "standby" on Windows Server 2008 R2

    - by Jaap
    In our SharePoint farm, our Web Front End servers all have loads of memory in "standby" mode, meaning very little is available for our IIS worker process. We have 32 GB of RAM in each of the boxes, and standby memory will creep up to about 28 GB, whereas the IIS worker process only seems to be using about 2 GB. Also, we've seen the machine use the swap file extensively while this memory was in standby, so I am starting to think that this memory in standby mode is stopping IIS from using it, forcing it to swap to disk, causing more performance problems. I used SysInternals RamMap to indentify what is being kept in memory, and it was able to tell me that almost everything in standby memory is of type "Mapped File". When I sort the files listed under the file summary tab in RamMap by file size, the largest files (around a few hundred meg each) are IIS log files and SharePoint log files. I would like to understand which process is loading these files into standby memory and why they are not being released. When I do an iisreset, it does not release the memory. Any ideas? Thanks!

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  • Memory Usage of SQL Server

    - by Ashish
    SQL Server instance on my server is using almost full memory available in my Physical Server. Say if i am having 8GB of RAM than SQL Server is using 7.8 GB of RAM from system. I also have read articles and also read many similar questions regarding same on this forum and i understand that memory is reserved and it is using memory. But i have 2 same servers and 2 SQL Servers, why this is happening on a single SQL Instance not on other. Also when i run DBCC MemoryStatus than it is showing up... VM Reserved 8282008 VM Committed 537936 so from this we know that SQL reserved whole 8GB memory, but why this VM Committed keeps increasing. What i understand is VM Committed is: VM Committed: This value shows the overall amount of VAS that SQL Server has committed. VAS that is committed has been associated with physical memory. So this is the memory SQL Server has committed (from this i understand that physical memory actually SQL Server is using at instance). So like to know the reason behind this ever increasing VM Committed memory on my server and not on another. Thanks in Advance.

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  • Understanding max JVM heap size

    - by Marcus
    I've read the max heap size on 32bit Windows is ~1.5GB which is due to the fact that the JVM requires contiguous memory. Can someone explain the concept of "contiguous memory" and why you only have max 1.5GB on Windows? Secondly, what then is the max heap size on 64 bit Windows and why is this different than what's available on 32 bit?

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  • Yet another Memory Leak Issue (memory is still gone when program terminates)- C program on SLES

    - by user1426181
    I run my C program on Suse Linux Enterprise that compresses several thousand large files (between 10MB and 100MB in size), and the program gets slower and slower as the program runs (it's running multi-threaded with 32 threads on a Intel Sandy Bridge board). When the program completes, and it's run again, it's still very slow. When I watch the program running, I see that the memory is being depleted while the program runs, which you would think is just a classic memory leak problem. But, with a normal malloc()/free() mismatch, I would expect all the memory to return when the program terminates. But, most of the memory doesn't get reclaimed when the program completes. The free or top command shows Mem: 63996M total, 63724M used, 272M free when the program is slowed down to a halt, but, after the termination, the free memory only grows back to about 3660M. When the program is rerun, the free memory is quickly used up. The top program only shows that the program, while running, is using at most 4% or so of the memory. I thought that it might be a memory fragmentation problem, but, I built a small test program that simulates all the memory allocation activity in the program (many randomized aspects were built in - size/quantity), and it always returns all the memory upon completion. So, I don't think that's it. Questions: Can there be a malloc()/free() mismatch that will lose memory permanently, i.e. even after the process completes? What other things in a C program (not C++) can cause permanent memory loss, i.e. after the program completes, and even the terminal window closes? Only a reboot brings the memory back. I've read other posts about files not being closed causing problems, but, I don't think I have that problem. Is it valid to be looking at top and free for the memory statistics, i.e. do they accurately describe the memory situation? They do seem to correspond to the slowness of the program. If the program only shows a 4% memory usage, will something like valgrind find this problem?

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  • Threading heap and stack

    - by DJ
    How memory is allocated in case of spawning a new thread, i.e how memory heap, memory stack, and threads are related? I know this is fundamental (.net framework concept) but somehow I am not much aware of this concept.

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  • Deleting Part of An Array in Java to Free Memory on Heap

    - by kate
    I am implementing a dynamic programming algorithm for the knapsack problem in Java. I declare the array and then initialize its size to be [number of objects][capacity of knapsack]. When my number of objects or my capacity gets too large, I get a memory error because I run out of space on the heap. My questions is: If I delete rows from my double array as I go along, will Java free the memory as I delete? Or does Java reserve that memory space for the size of the array I originally created? If it's the latter, is there a way to manually free the memory in Java? Thanks for your Help!

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  • Virtual memory on Linux doesn't add up?

    - by Brendan Long
    I was looking at System Monitor on Linux and noticed that Firefox is using 441 MB of memory, and several other applications are using 274, 257, 232, etc (adding up to over 3 GB of virtual memory). So I switch over to the Resources tab, and it says I'm using 462 MB of memory and not touching swap. I'm confused. What does the virtual memory amount mean then if the programs aren't actually using it. I was thinking maybe memory they've requested but aren't using, but how would the OS know that? I can't think of any "I might need this much memory in the future" function..

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