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  • Does btrfs balance also defragment files?

    - by pauldoo
    When I run btrfs filesystem balance, does this implicitly defragment files? I could imagine that balance simply reallocates each file extent separately, preserving the existing fragmentation. There is an FAQ entry, 'What does "balance" do?', which is unclear on this point: btrfs filesystem balance is an operation which simply takes all of the data and metadata on the filesystem, and re-writes it in a different place on the disks, passing it through the allocator algorithm on the way. It was originally designed for multi-device filesystems, to spread data more evenly across the devices (i.e. to "balance" their usage). This is particularly useful when adding new devices to a nearly-full filesystem. Due to the way that balance works, it also has some useful side-effects: If there is a lot of allocated but unused data or metadata chunks, a balance may reclaim some of that allocated space. This is the main reason for running a balance on a single-device filesystem. On a filesystem with damaged replication (e.g. a RAID-1 FS with a dead and removed disk), it will force the FS to rebuild the missing copy of the data on one of the currently active devices, restoring the RAID-1 capability of the filesystem.

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  • Which web site gives the most accurate indication of a programmer's capabilities?

    - by Jerry Coffin
    If you were hiring programmers, and could choose between one of (say) the top 100 coders on topcoder.com, or one of the top 100 on stackoverflow.com, which would you choose? At least to me, it would appear that topcoder.com gives a more objective evaluation of pure ability to solve problems and write code. At the same time, despite obvious technical capabilities, this person may lack any hint of social skills -- he may be purely a "lone coder", with little or no ability to help/work with others, may lack mentoring ability to help transfer his technical skills to others, etc. On the other hand, stackoverflow.com would at least appear to give a much better indication of peers' opinion of the coder in question, and the degree to which his presence and useful and helpful to others on the "team". At the same time, the scoring system is such that somebody who just throws up a lot of mediocre (or even poor answers) will almost inevitably accumulate a positive total of "reputation" points -- a single up-vote (perhaps just out of courtesy) will counteract the effects of no fewer than 5 down-votes, and others are discouraged (to some degree) from down-voting because they have to sacrifice their own reputation points to do so. At the same time, somebody who makes little or no technical contribution seems unlikely to accumulate a reputation that lands them (even close to) the top of the heap, so to speak. So, which provides a more useful indication of the degree to which this particular coder is likely to be useful to your organization? If you could choose between them, which set of coders would you rather have working on your team?

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  • Oh snap! My RPi was upgraded to 512MB! Woo-hoo!

    - by hinkmond
    I ordered a Raspberry Pi Model B (256MB) over 4 months ago on backorder. When it finally came I saw it was upgraded to the new half a gig model! Woot! But, all was not perfect. Gary C. told me the shipped configuration of the new RPi models didn't have the right firmware for 512MB, and I had to upgrade the start.elf in the /boot directory to recognize all of the 512MB RAM. I did a "free" command, and sure enough saw only 240MB. Sadness. But, Gary gave me a copy of his start.elf which worked after some trail and error. For anyone ordering the new RPi Model B w/512MB, here are the steps to get you going with full 512MB RAM: sudo apt-get update --fix-missing sudo apt-get upgrade --fix-missing # NOTE: This step takes at least a couple hours on a # fast network wget https://raw.github.com/raspberrypi/firmware/\ 164b0fe2b3b56081c7510df93bc1440aebe45f7e/boot/\ arm496_start.elf sudo mv /boot/start.elf /boot/orig-start.elf sudo mv arm496_start.elf /boot/start.elf sudo reboot free total used free shared buffers cached Mem: 497768 210596 287172 0 16892 169624 -/+ buffers/cache: 24080 473688 Swap: 102396 0 102396 So of course this means... (drumroll) there is now 498MB available for the Java Embedded heap! java -Xmx400m -version java version "1.7.0_06" Java(TM) SE Embedded Runtime Environment (build 1.7.0_06-b24, headless) Java HotSpot(TM) Embedded Client VM (build 23.2-b09, mixed mode) Yeah, baby! Hinkmond

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  • What is the "in-the-wire" size of a ethernet frame? 1518 or 1542?

    - by chrisapotek
    According to the table here, it says that MTU = 1500 bytes and that the payload part is 1500 - 42 bytes or 1458 bytes (<- this is actually wrong!). Now on top of that you have to add IPv4 and UDP headers, which are 28 bytes (20 IP + 8 UDP). That leaves my maximum possible application message to as 1430 bytes! But by looking for this number in the Internet I see 1472 instead. Am I doing this calculation wrong here? All I want to find out is the maximum application message I can send over the wire without the risk of fragmentation. It is definitely not 1500 because that includes the frame headers. Can someone help? The confusion is the the PAYLOAD can actually be as large as 1500 bytes and that's the MTU. So now what is the size in-the-wire for a payload of 1500? From that table it can be as big as 1542 bytes. So the maximum app messages I can send is 1472 (1500 - 20 (ip) - 8 (udp)) for a maximum in the wire size of 1542. It amazes me how things can get so complicated when they are actually simple. And I have not clue how someone came up with the number 1518 if the table says 1542.

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  • In APC+PHP, how much RAM is too much? Is it okay to set apc.shm_size to many GB?

    - by Jeremy Clarke
    On our server we have a LOT of RAM for our traffic levels (16GB). The HTTP processes regularly eat up all CPU and need to be restarted without even getting close to using swap memory, so I'm looking for ways to spend RAM to ease the load on Apache (and/or help the seperate MySQL server which may be breaking Apache). I have many WordPress installs on the HTTPD instance so APC sometimes uses as much as 900MB of ram (according to the apc.php charts). Just in case I have apc.shm_size set to 1600MB which is more than it needs but not more than I can spare. This means there is usually lots of extra RAM available to APC but also very little turnover and fragmentation is never more than 1%. Is this dangerous? Should I be slimming down APC to less than 1GB just on principle? Should I be expecting some turnover within APC in the name of bringing it's overall footprint down? Having so much memory devoted to APC means that in top/htop every single httpd process shows ~1.9GB in the VIRT memory column. Obviously this is shared memory and not used per-process, but could it be hurting our server? NOTE: The problem with the server remains unclear but the effect is that about 60 times a day all 8 CPU's fill up to 100% and everything stops working until Monit sees that Apache is broken and restarts it (Monin also saves the MySQL server). I'm not sure if APC is even part of the problem but I'm trying to optimize everything just in case.

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  • Gigabit network limited to 25MB/s by CPU. How to make it faster?

    - by netvope
    I have a Acer Aspire R1600-U910H with a nForce gigabit network adapter. The maximum TCP throughput of it is about 25MB/s, and apparently it is limited by the single core Intel Atom 230; when the maximum throughput is reached, the CPU usage is about 50%-60%, which corresponds to full utilization considering this is a Hyper-threading enabled CPU. The same problem occurs on both Windows XP and on Ubuntu 8.04. On Windows, I have installed the latest nForce chipset driver, disabled power saving features, and enabled checksum offload. On Linux, the default driver has checksum offload enabled. There is no Linux driver available on Nvidia's website. ethtool -k eth0 shows that checksum offload is enabled: Offload parameters for eth0: rx-checksumming: on tx-checksumming: on scatter-gather: on tcp segmentation offload: on udp fragmentation offload: off generic segmentation offload: off The following is the output of powertop when the network is idle: Wakeups-from-idle per second : 61.9 interval: 10.0s no ACPI power usage estimate available Top causes for wakeups: 90.9% (101.3) <interrupt> : eth0 4.5% ( 5.0) iftop : schedule_timeout (process_timeout) 1.8% ( 2.0) <kernel core> : clocksource_register (clocksource_watchdog) 0.9% ( 1.0) dhcdbd : schedule_timeout (process_timeout) 0.5% ( 0.6) <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer) And when the maximum throughput of about 25MB/s is reached: Wakeups-from-idle per second : 11175.5 interval: 10.0s no ACPI power usage estimate available Top causes for wakeups: 99.9% (22097.4) <interrupt> : eth0 0.0% ( 5.0) iftop : schedule_timeout (process_timeout) 0.0% ( 2.0) <kernel core> : clocksource_register (clocksource_watchdog) 0.0% ( 1.0) dhcdbd : schedule_timeout (process_timeout) 0.0% ( 0.6) <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer) Notice the 20000 interrupts per second. Could this be the cause for the high CPU usage and low throughput? If so, how can I improve the situation? The other computers in the network can usually transfer at 50+MB/s without problems. And a minor question: How can I find out what is the driver in use for eth0?

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  • Is there an objective way to measure slowness of PC/WINDOWS?

    - by ekms
    We've a lot of users that usually complain about that his PC is "slow". (we use win XP). We usually check startup programs, virus, fragmentation, disk health and common problems that causes slowness (Symantec AV drops disk to 1mb/s , or a seagate HD firmware error in certain models), but in those cases the slowness is pretty evident. In other hand, the most common is the user complaining about his pc but for us looks OK, even in 6 years old desktops. People sometimes even complains about his new quad core desktops speed!!! So, we are asking if there's a way to OBJECTIVELY check that a computer didn't dropped its performance, compared with similar ones o previous measures, specially for work use (I don't think that 3dmark benchmark o similar may help). The only thing that I found that was useful is HDTune, but it only check hard disk performance. Basically, what we want is something that enable us to say to our users "see? your PC is as slow as was three years ago! stop complaining! Is all in your head!"

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  • Recover file from NTFS after it was formatted twice

    - by Phil
    I'm running Linux Mint and have a 2TB drive that I formatted as NTFS. I copied ~120GB of files from another computer to the 2TB drive, removing the files from the other computer as I did so. When they were all on the 2TB drive, I zipped them up as file "Gold.tar.gz". Then I reformatted the 2TB drive as ext3 in a moment of absolute stupidity. I formatted the 2TB back to NTFS, but of course everything is gone. Here is what I have tried: TestDisk -- won't find any lost partitions or undelete files, just the current empty one PhotoRec -- seems to only find some broken text files and misidentify their extensions. It never finds the 100's of avi files I had (before the 120GB copy, I already had 750GB on the drive full of avi files) or anything else that would show me it's working properly. Using dd I recovered the first 512MB of the drive and went hunting through it. I found all of the file as MFT entries, including the file "Gold.tar.gz" in a 2048 byte MFT record. I'm looking now for some way of either (1) telling PhotoRec to look at that record, or (2) analyze the MFT record myself and discover the sectors holding the data; I can piece it all together using dd and join the binary output if it's fragmented. One last thing - from the moment I got this drive a few days ago to the incident, there were only file copies made to it and no deletes. I formatted as NTFS, then copied thousands of files, then made a tar.gz, then reformatted to ext3, then reformatted to NTFS again. I'm hoping that the size of the drive and fact that there was no file modification/deleting happening makes for minimal file fragmentation.

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  • Dealing with numerous, simultaneous sounds in unity

    - by luxchar
    I've written a custom class that creates a fixed number of audio sources. When a new sound is played, it goes through the class, which creates a queue of sounds that will be played during that frame. The sounds that are closer to the camera are given preference. If new sounds arrive in the next frame, I have a complex set of rules that determines how to replace the old ones. Ideally, "big" or "important" sounds should not be replaced by small ones. Sound replacement is necessary since the game can be fast-paced at times, and should try to play new sounds by replacing old ones. Otherwise, there can be "silent" moments when an old sound is about to stop playing and isn't replaced right away by a new sound. The drawback of replacing old sounds right away is that there is a harsh transition from the old sound clip to the new one. But I wonder if I could just remove that management logic altogether, and create audio sources on the fly for new sounds. I could give "important" sounds more priority (closer to 0 in the corresponding property) as opposed to less important ones, and let Unity take care of culling out sound effects that exceed the channel limit. The only drawback is that it requires many heap allocations. I wonder what strategy people use here?

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  • Impact of Server Failure on Coherence Request Processing

    - by jpurdy
    Requests against a given cache server may be temporarily blocked for several seconds following the failure of other cluster members. This may cause issues for applications that can not tolerate multi-second response times even during failover processing (ignoring for the moment that in practice there are a variety of issues that make such absolute guarantees challenging even when there are no server failures). In general, Coherence is designed around the principle that failures in one member should not affect the rest of the cluster if at all possible. However, it's obvious that if that failed member was managing a piece of state that another member depends on, the second member will need to wait until a new member assumes responsibility for managing that state. This transfer of responsibility is (as of Coherence 3.7) performed by the primary service thread for each cache service. The finest possible granularity for transferring responsibility is a single partition. So the question becomes how to minimize the time spent processing each partition. Here are some optimizations that may reduce this period: Reduce the size of each partition (by increasing the partition count) Increase the number of JVMs across the cluster (increasing the total number of primary service threads) Increase the number of CPUs across the cluster (making sure that each JVM has a CPU core when needed) Re-evaluate the set of configured indexes (as these will need to be rebuilt when a partition moves) Make sure that the backing map is as fast as possible (in most cases this means running on-heap) Make sure that the cluster is running on hardware with fast CPU cores (since the partition processing is single-threaded) As always, proper testing is required to make sure that configuration changes have the desired effect (and also to quantify that effect).

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  • When and how does one become a good programmer these days? [closed]

    - by YoungMoney
    I mean, good enough to make software people want and get paid for it. Maybe even good enough to launch a company or something. I'm also concerned that I'm not applying the finer points of my algorithms/data structures/software design knowledge. Background: I'm 20 and have been struggling with programming for about two years now, trying to become a software engineer. I started with a few university courses that I did quite poorly in. I learned how to make websites with HTML/JavaScript and PHP/MySQL, but feel like I know very relevant theory for making good databases - how does something like Facebook serve hundreds of millions of people? What would be smart ways to store data? I don't know. Now I'm doing some android application development, but again I have no idea about good Java design theory (I use static variables like they're going out of fashion) and feel more like I'm gluing stuff together and letting Eclipse slowly autocomplete my project. In short, I'm not sure if I'm becoming a legitimate software developer or just "doing what's cool". At least I've taken some data structures and Algorithms courses and plan to take more in the next years. But I'm having a really tough time applying this stuff to my fun little apps that I'm building. Every language higher level than C++ seems to have its own quicksort function already built-in, for example. Similarly, I can't remember ever needing to implement a linked-list, heap, binary tree, or or worry about pointers and memory management. But maybe this is a good thing so that I focus on other things? I'm not too sure what those other things are though. Hopefully something more than building another photo sharing app. Anyways that's it for me, I look forward to your responses!

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  • Where can these be posted besides the Python Cookbook?

    - by Noctis Skytower
    Whitespace Assembler #! /usr/bin/env python """Assembler.py Compiles a program from "Assembly" folder into "Program" folder. Can be executed directly by double-click or on the command line. Give name of *.WSA file without extension (example: stack_calc).""" ################################################################################ __author__ = 'Stephen "Zero" Chappell <[email protected]>' __date__ = '14 March 2010' __version__ = '$Revision: 3 $' ################################################################################ import string from Interpreter import INS, MNEMONIC ################################################################################ def parse(code): program = [] process_virtual(program, code) process_control(program) return tuple(program) def process_virtual(program, code): for line, text in enumerate(code.split('\n')): if not text or text[0] == '#': continue if text.startswith('part '): parse_part(program, line, text[5:]) elif text.startswith(' '): parse_code(program, line, text[5:]) else: syntax_error(line) def syntax_error(line): raise SyntaxError('Line ' + str(line + 1)) ################################################################################ def process_control(program): parts = get_parts(program) names = dict(pair for pair in zip(parts, generate_index())) correct_control(program, names) def get_parts(program): parts = [] for ins in program: if isinstance(ins, tuple): ins, arg = ins if ins == INS.PART: if arg in parts: raise NameError('Part definition was found twice: ' + arg) parts.append(arg) return parts def generate_index(): index = 1 while True: yield index index *= -1 if index > 0: index += 1 def correct_control(program, names): for index, ins in enumerate(program): if isinstance(ins, tuple): ins, arg = ins if ins in HAS_LABEL: if arg not in names: raise NameError('Part definition was never found: ' + arg) program[index] = (ins, names[arg]) ################################################################################ def parse_part(program, line, text): if not valid_label(text): syntax_error(line) program.append((INS.PART, text)) def valid_label(text): if not between_quotes(text): return False label = text[1:-1] if not valid_name(label): return False return True def between_quotes(text): if len(text) < 3: return False if text.count('"') != 2: return False if text[0] != '"' or text[-1] != '"': return False return True def valid_name(label): valid_characters = string.ascii_letters + string.digits + '_' valid_set = frozenset(valid_characters) label_set = frozenset(label) if len(label_set - valid_set) != 0: return False return True ################################################################################ from Interpreter import HAS_LABEL, Program NO_ARGS = Program.NO_ARGS HAS_ARG = Program.HAS_ARG TWO_WAY = tuple(set(NO_ARGS) & set(HAS_ARG)) ################################################################################ def parse_code(program, line, text): for ins, word in enumerate(MNEMONIC): if text.startswith(word): check_code(program, line, text[len(word):], ins) break else: syntax_error(line) def check_code(program, line, text, ins): if ins in TWO_WAY: if text: number = parse_number(line, text) program.append((ins, number)) else: program.append(ins) elif ins in HAS_LABEL: text = parse_label(line, text) program.append((ins, text)) elif ins in HAS_ARG: number = parse_number(line, text) program.append((ins, number)) elif ins in NO_ARGS: if text: syntax_error(line) program.append(ins) else: syntax_error(line) def parse_label(line, text): if not text or text[0] != ' ': syntax_error(line) text = text[1:] if not valid_label(text): syntax_error(line) return text ################################################################################ def parse_number(line, text): if not valid_number(text): syntax_error(line) return int(text) def valid_number(text): if len(text) < 2: return False if text[0] != ' ': return False text = text[1:] if '+' in text and '-' in text: return False if '+' in text: if text.count('+') != 1: return False if text[0] != '+': return False text = text[1:] if not text: return False if '-' in text: if text.count('-') != 1: return False if text[0] != '-': return False text = text[1:] if not text: return False valid_set = frozenset(string.digits) value_set = frozenset(text) if len(value_set - valid_set) != 0: return False return True ################################################################################ ################################################################################ from Interpreter import partition_number VMC_2_TRI = { (INS.PUSH, True): (0, 0), (INS.COPY, False): (0, 2, 0), (INS.COPY, True): (0, 1, 0), (INS.SWAP, False): (0, 2, 1), (INS.AWAY, False): (0, 2, 2), (INS.AWAY, True): (0, 1, 2), (INS.ADD, False): (1, 0, 0, 0), (INS.SUB, False): (1, 0, 0, 1), (INS.MUL, False): (1, 0, 0, 2), (INS.DIV, False): (1, 0, 1, 0), (INS.MOD, False): (1, 0, 1, 1), (INS.SET, False): (1, 1, 0), (INS.GET, False): (1, 1, 1), (INS.PART, True): (2, 0, 0), (INS.CALL, True): (2, 0, 1), (INS.GOTO, True): (2, 0, 2), (INS.ZERO, True): (2, 1, 0), (INS.LESS, True): (2, 1, 1), (INS.BACK, False): (2, 1, 2), (INS.EXIT, False): (2, 2, 2), (INS.OCHR, False): (1, 2, 0, 0), (INS.OINT, False): (1, 2, 0, 1), (INS.ICHR, False): (1, 2, 1, 0), (INS.IINT, False): (1, 2, 1, 1) } ################################################################################ def to_trinary(program): trinary_code = [] for ins in program: if isinstance(ins, tuple): ins, arg = ins trinary_code.extend(VMC_2_TRI[(ins, True)]) trinary_code.extend(from_number(arg)) else: trinary_code.extend(VMC_2_TRI[(ins, False)]) return tuple(trinary_code) def from_number(arg): code = [int(arg < 0)] if arg: for bit in reversed(list(partition_number(abs(arg), 2))): code.append(bit) return code + [2] return code + [0, 2] to_ws = lambda trinary: ''.join(' \t\n'[index] for index in trinary) def compile_wsa(source): program = parse(source) trinary = to_trinary(program) ws_code = to_ws(trinary) return ws_code ################################################################################ ################################################################################ import os import sys import time import traceback def main(): name, source, command_line, error = get_source() if not error: start = time.clock() try: ws_code = compile_wsa(source) except: print('ERROR: File could not be compiled.\n') traceback.print_exc() error = True else: path = os.path.join('Programs', name + '.ws') try: open(path, 'w').write(ws_code) except IOError as err: print(err) error = True else: div, mod = divmod((time.clock() - start) * 1000, 1) args = int(div), '{:.3}'.format(mod)[1:] print('DONE: Comipled in {}{} ms'.format(*args)) handle_close(error, command_line) def get_source(): if len(sys.argv) > 1: command_line = True name = sys.argv[1] else: command_line = False try: name = input('Source File: ') except: return None, None, False, True print() path = os.path.join('Assembly', name + '.wsa') try: return name, open(path).read(), command_line, False except IOError as err: print(err) return None, None, command_line, True def handle_close(error, command_line): if error: usage = 'Usage: {} <assembly>'.format(os.path.basename(sys.argv[0])) print('\n{}\n{}'.format('-' * len(usage), usage)) if not command_line: time.sleep(10) ################################################################################ if __name__ == '__main__': main() Whitespace Helpers #! /usr/bin/env python """Helpers.py Includes a function to encode Python strings into my WSA format. Has a "PRINT_LINE" function that can be copied to a WSA program. Contains a "PRINT" function and documentation as an explanation.""" ################################################################################ __author__ = 'Stephen "Zero" Chappell <[email protected]>' __date__ = '14 March 2010' __version__ = '$Revision: 1 $' ################################################################################ def encode_string(string, addr): print(' push', addr) print(' push', len(string)) print(' set') addr += 1 for offset, character in enumerate(string): print(' push', addr + offset) print(' push', ord(character)) print(' set') ################################################################################ # Prints a string with newline. # push addr # call "PRINT_LINE" """ part "PRINT_LINE" call "PRINT" push 10 ochr back """ ################################################################################ # def print(array): # if len(array) <= 0: # return # offset = 1 # while len(array) - offset >= 0: # ptr = array.ptr + offset # putch(array[ptr]) # offset += 1 """ part "PRINT" # Line 1-2 copy get less "__PRINT_RET_1" copy get zero "__PRINT_RET_1" # Line 3 push 1 # Line 4 part "__PRINT_LOOP" copy copy 2 get swap sub less "__PRINT_RET_2" # Line 5 copy 1 copy 1 add # Line 6 get ochr # Line 7 push 1 add goto "__PRINT_LOOP" part "__PRINT_RET_2" away part "__PRINT_RET_1" away back """ Whitespace Interpreter #! /usr/bin/env python """Interpreter.py Runs programs in "Programs" and creates *.WSO files when needed. Can be executed directly by double-click or on the command line. If run on command line, add "ASM" flag to dump program assembly.""" ################################################################################ __author__ = 'Stephen "Zero" Chappell <[email protected]>' __date__ = '14 March 2010' __version__ = '$Revision: 4 $' ################################################################################ def test_file(path): disassemble(parse(trinary(load(path))), True) ################################################################################ load = lambda ws: ''.join(c for r in open(ws) for c in r if c in ' \t\n') trinary = lambda ws: tuple(' \t\n'.index(c) for c in ws) ################################################################################ def enum(names): names = names.replace(',', ' ').split() space = dict((reversed(pair) for pair in enumerate(names)), __slots__=()) return type('enum', (object,), space)() INS = enum('''\ PUSH, COPY, SWAP, AWAY, \ ADD, SUB, MUL, DIV, MOD, \ SET, GET, \ PART, CALL, GOTO, ZERO, LESS, BACK, EXIT, \ OCHR, OINT, ICHR, IINT''') ################################################################################ def parse(code): ins = iter(code).__next__ program = [] while True: try: imp = ins() except StopIteration: return tuple(program) if imp == 0: # [Space] parse_stack(ins, program) elif imp == 1: # [Tab] imp = ins() if imp == 0: # [Tab][Space] parse_math(ins, program) elif imp == 1: # [Tab][Tab] parse_heap(ins, program) else: # [Tab][Line] parse_io(ins, program) else: # [Line] parse_flow(ins, program) def parse_number(ins): sign = ins() if sign == 2: raise StopIteration() buffer = '' code = ins() if code == 2: raise StopIteration() while code != 2: buffer += str(code) code = ins() if sign == 1: return int(buffer, 2) * -1 return int(buffer, 2) ################################################################################ def parse_stack(ins, program): code = ins() if code == 0: # [Space] number = parse_number(ins) program.append((INS.PUSH, number)) elif code == 1: # [Tab] code = ins() number = parse_number(ins) if code == 0: # [Tab][Space] program.append((INS.COPY, number)) elif code == 1: # [Tab][Tab] raise StopIteration() else: # [Tab][Line] program.append((INS.AWAY, number)) else: # [Line] code = ins() if code == 0: # [Line][Space] program.append(INS.COPY) elif code == 1: # [Line][Tab] program.append(INS.SWAP) else: # [Line][Line] program.append(INS.AWAY) def parse_math(ins, program): code = ins() if code == 0: # [Space] code = ins() if code == 0: # [Space][Space] program.append(INS.ADD) elif code == 1: # [Space][Tab] program.append(INS.SUB) else: # [Space][Line] program.append(INS.MUL) elif code == 1: # [Tab] code = ins() if code == 0: # [Tab][Space] program.append(INS.DIV) elif code == 1: # [Tab][Tab] program.append(INS.MOD) else: # [Tab][Line] raise StopIteration() else: # [Line] raise StopIteration() def parse_heap(ins, program): code = ins() if code == 0: # [Space] program.append(INS.SET) elif code == 1: # [Tab] program.append(INS.GET) else: # [Line] raise StopIteration() def parse_io(ins, program): code = ins() if code == 0: # [Space] code = ins() if code == 0: # [Space][Space] program.append(INS.OCHR) elif code == 1: # [Space][Tab] program.append(INS.OINT) else: # [Space][Line] raise StopIteration() elif code == 1: # [Tab] code = ins() if code == 0: # [Tab][Space] program.append(INS.ICHR) elif code == 1: # [Tab][Tab] program.append(INS.IINT) else: # [Tab][Line] raise StopIteration() else: # [Line] raise StopIteration() def parse_flow(ins, program): code = ins() if code == 0: # [Space] code = ins() label = parse_number(ins) if code == 0: # [Space][Space] program.append((INS.PART, label)) elif code == 1: # [Space][Tab] program.append((INS.CALL, label)) else: # [Space][Line] program.append((INS.GOTO, label)) elif code == 1: # [Tab] code = ins() if code == 0: # [Tab][Space] label = parse_number(ins) program.append((INS.ZERO, label)) elif code == 1: # [Tab][Tab] label = parse_number(ins) program.append((INS.LESS, label)) else: # [Tab][Line] program.append(INS.BACK) else: # [Line] code = ins() if code == 2: # [Line][Line] program.append(INS.EXIT) else: # [Line][Space] or [Line][Tab] raise StopIteration() ################################################################################ MNEMONIC = '\ push copy swap away add sub mul div mod set get part \ call goto zero less back exit ochr oint ichr iint'.split() HAS_ARG = [getattr(INS, name) for name in 'PUSH COPY AWAY PART CALL GOTO ZERO LESS'.split()] HAS_LABEL = [getattr(INS, name) for name in 'PART CALL GOTO ZERO LESS'.split()] def disassemble(program, names=False): if names: names = create_names(program) for ins in program: if isinstance(ins, tuple): ins, arg = ins assert ins in HAS_ARG has_arg = True else: assert INS.PUSH <= ins <= INS.IINT has_arg = False if ins == INS.PART: if names: print(MNEMONIC[ins], '"' + names[arg] + '"') else: print(MNEMONIC[ins], arg) elif has_arg and ins in HAS_ARG: if ins in HAS_LABEL and names: assert arg in names print(' ' + MNEMONIC[ins], '"' + names[arg] + '"') else: print(' ' + MNEMONIC[ins], arg) else: print(' ' + MNEMONIC[ins]) ################################################################################ def create_names(program): names = {} number = 1 for ins in program: if isinstance(ins, tuple) and ins[0] == INS.PART: label = ins[1] assert label not in names names[label] = number_to_name(number) number += 1 return names def number_to_name(number): name = '' for offset in reversed(list(partition_number(number, 27))): if offset: name += chr(ord('A') + offset - 1) else: name += '_' return name def partition_number(number, base): div, mod = divmod(number, base) yield mod while div: div, mod = divmod(div, base) yield mod ################################################################################ CODE = (' \t\n', ' \n ', ' \t \t\n', ' \n\t', ' \n\n', ' \t\n \t\n', '\t ', '\t \t', '\t \n', '\t \t ', '\t \t\t', '\t\t ', '\t\t\t', '\n \t\n', '\n \t \t\n', '\n \n \t\n', '\n\t \t\n', '\n\t\t \t\n', '\n\t\n', '\n\n\n', '\t\n ', '\t\n \t', '\t\n\t ', '\t\n\t\t') EXAMPLE = ''.join(CODE) ################################################################################ NOTES = '''\ STACK ===== push number copy copy number swap away away number MATH ==== add sub mul div mod HEAP ==== set get FLOW ==== part label call label goto label zero label less label back exit I/O === ochr oint ichr iint''' ################################################################################ ################################################################################ class Stack: def __init__(self): self.__data = [] # Stack Operators def push(self, number): self.__data.append(number) def copy(self, number=None): if number is None: self.__data.append(self.__data[-1]) else: size = len(self.__data) index = size - number - 1 assert 0 <= index < size self.__data.append(self.__data[index]) def swap(self): self.__data[-2], self.__data[-1] = self.__data[-1], self.__data[-2] def away(self, number=None): if number is None: self.__data.pop() else: size = len(self.__data) index = size - number - 1 assert 0 <= index < size del self.__data[index:-1] # Math Operators def add(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix + suffix) def sub(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix - suffix) def mul(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix * suffix) def div(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix // suffix) def mod(self): suffix = self.__data.pop() prefix = self.__data.pop() self.__data.append(prefix % suffix) # Program Operator def pop(self): return self.__data.pop() ################################################################################ class Heap: def __init__(self): self.__data = {} def set_(self, addr, item): if item: self.__data[addr] = item elif addr in self.__data: del self.__data[addr] def get_(self, addr): return self.__data.get(addr, 0) ################################################################################ import os import zlib import msvcrt import pickle import string class CleanExit(Exception): pass NOP = lambda arg: None DEBUG_WHITESPACE = False ################################################################################ class Program: NO_ARGS = INS.COPY, INS.SWAP, INS.AWAY, INS.ADD, \ INS.SUB, INS.MUL, INS.DIV, INS.MOD, \ INS.SET, INS.GET, INS.BACK, INS.EXIT, \ INS.OCHR, INS.OINT, INS.ICHR, INS.IINT HAS_ARG = INS.PUSH, INS.COPY, INS.AWAY, INS.PART, \ INS.CALL, INS.GOTO, INS.ZERO, INS.LESS def __init__(self, code): self.__data = code self.__validate() self.__build_jump() self.__check_jump() self.__setup_exec() def __setup_exec(self): self.__iptr = 0 self.__stck = stack = Stack() self.__heap = Heap() self.__cast = [] self.__meth = (stack.push, stack.copy, stack.swap, stack.away, stack.add, stack.sub, stack.mul, stack.div, stack.mod, self.__set, self.__get, NOP, self.__call, self.__goto, self.__zero, self.__less, self.__back, self.__exit, self.__ochr, self.__oint, self.__ichr, self.__iint) def step(self): ins = self.__data[self.__iptr] self.__iptr += 1 if isinstance(ins, tuple): self.__meth[ins[0]](ins[1]) else: self.__meth[ins]() def run(self): while True: ins = self.__data[self.__iptr] self.__iptr += 1 if isinstance(ins, tuple): self.__meth[ins[0]](ins[1]) else: self.__meth[ins]() def __oint(self): for digit in str(self.__stck.pop()): msvcrt.putwch(digit) def __ichr(self): addr = self.__stck.pop() # Input Routine while msvcrt.kbhit(): msvcrt.getwch() while True: char = msvcrt.getwch() if char in '\x00\xE0': msvcrt.getwch() elif char in string.printable: char = char.replace('\r', '\n') msvcrt.putwch(char) break item = ord(char) # Storing Number self.__heap.set_(addr, item) def __iint(self): addr = self.__stck.pop() # Input Routine while msvcrt.kbhit(): msvcrt.getwch() buff = '' char = msvcrt.getwch() while char != '\r' or not buff: if char in '\x00\xE0': msvcrt.getwch() elif char in '+-' and not buff: msvcrt.putwch(char) buff += char elif '0' <= char <= '9': msvcrt.putwch(char) buff += char elif char == '\b': if buff: buff = buff[:-1] msvcrt.putwch(char) msvcrt.putwch(' ') msvcrt.putwch(char) char = msvcrt.getwch() msvcrt.putwch(char) msvcrt.putwch('\n') item = int(buff) # Storing Number self.__heap.set_(addr, item) def __goto(self, label): self.__iptr = self.__jump[label] def __zero(self, label): if self.__stck.pop() == 0: self.__iptr = self.__jump[label] def __less(self, label): if self.__stck.pop() < 0: self.__iptr = self.__jump[label] def __exit(self): self.__setup_exec() raise CleanExit() def __set(self): item = self.__stck.pop() addr = self.__stck.po

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  • top tweets WebLogic Partner Community – June 2012

    - by JuergenKress
    Send your tweets @wlscommunity #WebLogicCommunity and follow us at http://twitter.com/wlscommunity OTNArchBeat? Free Virtual Developer Day: Oracle ADF and Oracle Fusion Middleware Development http://bit.ly/MxuNAg AMIS, Oracle & Java? Checklist veearts nu ook op iPad. @amis_services Mobile integratie met Oracle Fusion Middleware http://dld.bz/buwsM #OSB #SOA WhitehorsesWhiteblog: Troubleshoot JVM crashes of Weblogic: CompilerThread (http://bit.ly/KcGzZK) Jon petter hjulstad E-vita is now Apps Grid Specialized! ODTUG Fusion Middleware Sessions RT @OTNArchBeat: ODTUG Kscope12 - June 24-28 - San Antonio, TX http://bit.ly/LlWkNV OTNArchBeat? Free Event: Modern #Java Development, in/outside the Enterprise - May 30 - Redwood Shores, CA http://bit.ly/LfB79a ADF Community DE? Oracle Advanced ADF 11g Partner Workshop Düsseldorf /Germany (english) June 26-29, click here to see Nicolas Lorain? Best Practices for #JavaFX 2 Enterprise Applications (Part Two) http://buff.ly/Lk1DBn by Jim Weaver shay shmeltzer? #Oracle Developers in #Israel - don't miss the free #ADF workshop July 2nd - get hands-on with Oracle ADF -here OTNArchBeat? Java at JAXconf | Tori Wieldt http://bit.ly/LdoLS2 Anand Akela? #Oracle Customers and Partners – Get your free pass to @CloudExpo in New York, June 11 to 14, http://goo.gl/RpYFT <- Stop by booth #511 OracleSupport_WLS? Did you know that since 3/15/12 #WebLogic Server 12.1.1.0 is certified for production with JDK 7? http://bit.ly/IYJE0L Sharat? Highly useful #JavaFX best practices blog by @JavaFXpert More details here ADF EMG How to set up a productive ADF Dev Env - discussion started by @baigsorcl. Click here to Read and comment. OracleSupport_WLS Upcoming #webcast: Diagnosing #weblogic performance issues through #java thread dumps http://bit.ly/M4O9qF My Oracle Support? New to Oracle Support? - Webcast on Support Basics webcast May 22 10:30 Central Europe. Register @ http://bit.ly/J8o0WG Mohamad Afshar? Cloud Expo – Oracle Customers and Partners – get your free pass to Cloud Expo in New York, June 11 to 14, http://goo.gl/RpYFT OTNArchBeat Oracle VM 3.1 is here | @Ronenkofman http://bit.ly/JriWTq Oracle Exalogic? RT @D0uglasPhillips: ExalogicTV New Video Introducing Oracle Secure Global Desktop for #Exalogic!! http://bit.ly/nwkrCu OracleBlogs? Java EE6 and WebLogic YouTube video channels http://ow.ly/1jVcYJ Oracle WebLogic RT @aleftik: Excited to spend some time today playing around with the WebSockets SDK http://bit.ly/NoTtri WebLogic Community Java EE6 and WebLogic YouTube video channels http://wp.me/p1LMIb-h0 OracleSupport_WLS New tutorial! How to use the #JMS #API to create a message producer with #GlassFish and #NetBeans http://bit.ly/Juqjn JDeveloper & ADF? Tip when installing JDeveloper 11.1.2.2.0 version http://dlvr.it/1b48s1 WebLogic Community Middleware Oracle Excellence Awards 2012 – HAPPY NEW YEAR! Click here to read WebLogicCommunity #opn #oracle#Specialization #opnaward Steven Davelaar? Improve performance of your ADF app using lazy, on-demand querying of detail view objects: Click here OracleBlogs? Middleware Oracle Excellence Awards 2012 & HAPPY NEW YEAR! http://ow.ly/1kahzZ OracleSupport_WLS Upgrading from #weblogic 9.2.x to 10.3.x? http://bit.ly/Kqzl9N AMIS, Oracle & Java “@JDeveloper: Logout from an ADF application http://dlvr.it/1fQBnm” WebLogic Community UK OUG call for papers–your middleware success! Click here #UKOUG #soacommunity #OPN Whitehorses Whiteblog: Enterprise Manager: Manage your Fusion Middleware logfiles (http://bit.ly/KQlZkR) WebLogic Community? @Jphjulstad HI Jon, should we send Pizza when you go in production with your WebLogic 12c project? Whish you success! #WebLogicCommunity Sabine Leitner ADF Einsteigerworkshops je 2 Tage im Juni in HAM, BLN, HANN #Oracle #WLS http://bit.ly/LcOIzB @OracleWebLogic @OracleAppGrid@soacommunity Andreas Koop new post Java Heap Monitor in JDeveloper http://bit.ly/LgSk85 Sabine Leitner? #Oracle Kundentag mit Vorträgen von Sparkasse, Schufa, LBBW, Allianz über FMW & Exa Lösungen! 21.06. FRA http://bit.ly/JtwE3v @wlscommunity NetBeans Team RT @chadlung: Installing and configuring #NetBeans 7.1.2 and the #Java JDK 1.7 on OS X: http://www.giantflyingsaucer.com/blog/p=3760 #osx WebLogic Community Happy New Year #WeblogicCommunity thanks for the business! Time for a drink http://pic.twitter.com/K34KFbvH WebLogic Community UK OUG call for papers&ndash;your middleware success! http://wp.me/p1LMIb-gU WebLogic Community? Middleware Oracle Excellence Awards 2012 - HAPPY NEW YEAR! http://wp.me/p1LMIb-h6 Oracle WebLogic? RT @wlscommunity: WebLogic World Record Two Processor Result with SPECjEnterprise2010 Benchmark Click here to read #weblogic #sunfire #li Marc? Relocate wlst script for all the logfiles in your domain @wlscommunity, http://tinyurl.com/btbjcco WebLogic Community WebLogic World Record Two Processor Result with SPECjEnterprise2010 Benchmark Click here #WebLogicCommunity #weblogic #sunfire Oracle WebLogic MIss a WebLogic Devcast webinar? Catch any of the replays in the series on-demand! #WebLogic #JavaEE #coherence http://bit.ly/LNGa4p JDeveloper & ADF? Bean DataControl - Edit table records http://dlvr.it/1ZWqCx Justin Kestelyn? Contents of "Virtual Developer Day: Java SE 7 and JavaFX 2.0" are now avail on demand; no reg http://tinyurl.com/78nxnyo Frank Nimphius? Preparing 12c new features for DOAG 2012 Development - June 14th in Bonn (http://development.doag.org) WebLogic Community? Middleware Oracle Excellence Awards 2012&ndash;HAPPY NEW YEAR! http://wp.me/p1LMIb-he JDeveloper & ADF Placeholder Watermarks with ADF 11.1.2 http://dlvr.it/1ZWDc9 Oracle ACE Program? May edition #ACE newsletter now available online. http://bit.ly/LKA2de chriscmuir New blog post: Which JDeveloper is right for me? http://bit.ly/J8sj9e GlassFish? Transactional Interceptors in Java EE 7 - Request for feedback: Linda described how EJB's container-managed tr http://bit.ly/KKuGNJ OracleEnterpriseMgr Oracle Application Testing Suite 12.1 Debuts at StarEast 2012 http://ow.ly/aXcv8 #em12c JAX London First set of speaker session announced for #JAXLondon see: http://bit.ly/L0HSME OTNArchBeat? Oracle Cloud Conference: dates and locations worldwide http://bit.ly/JgNeID NetBeans Team? Video: Create and debug a TestNG test class in #NetBeans IDE: http://ow.ly/b7NEW NetBeans Team #NetBeans tip: Code Template for #Kohana #PHP Framework: http://ow.ly/aWIvY Robin? Started to use the #Oracle #WebLogic Server #Maven Plugin. Really awesome to install a complete #WLS with "mvn wls:install" !@wlscommunity OTNArchBeat? Free Event: Modern #Java Development, in/outside the Enterprise - May 30 - Redwood Shores, CA http://bit.ly/JIN9tf OracleBlogs WebLogic Partner Community Newsletter May 2012 http://ow.ly/1k5TeG Java Certification? Java SE 7 Fundamentals course now available On Demand. Watch a preview now: http://ow.ly/aWYgD Whitehorses Whiteblog: Native IO in WebLogic on Solaris 11 X64 (http://bit.ly/KGM4mp) NetBeans Team? Quick video of FindBugs Integration in #NetBeans IDE 7.2: http://ow.ly/aNece NetBeans Team #JavaFX Scene Builder Docs Updated for 2.2 and #NetBeans 7.2 dev builds: http://ow.ly/b7Nie Duncan Mills? New blog posting on implementing input field watermarks with ADF Faces 11.1.2 Click here #adf WebLogic Community? WebLogic Partner Community Newsletter May 2012 http://wp.me/p1LMIb-h4 OracleBlogs? UK OUG call for papersyour middleware success! http://ow.ly/1jNs49 Nicolas Lorain? Java tip: Deploying #JavaFX apps to multiple environments - JavaWorld http://buff.ly/KDADvu Adam Bien? Java EE and How to Specify The Unconventional With Convention Over Configuration [Free Article]: The free http://bit.ly/JEUkUf Owen Hughes and team?#Oracle #Exalogic #Performance: What? How? Why? Click here GlassFish? SecuritEE in the Cloud: Java EE 7 and the Cloud theme continue to move full steam ahead. In a PaaS environment http://bit.ly/K2RPte JDeveloper & ADF? How to Align Managed Bean Scope and Bean Data Control in Oracle ADF http://dlvr.it/1dngxQ Andrejus Baranovskis Missing New Feature in JDev (11.1.2.2.0) - ADF Methods Security http://fb.me/1jQM1enls OracleSupport_WLS? Tutorial on managing #HTTP Sessions in a #Weblogic #Cluster http://bit.ly/JshESe Oracle WebLogic? ZeroTurnaround developer report: #Spring keeps getting heavier, and #Java EE keeps getting lighter http://bit.ly/JDmKy2 JDeveloper & ADF? How to Search in Views - Part 4 || Oracle ADF http://dlvr.it/1dpDjZ WebLogic Community Java Message Service with Java and Spring Framework on Oracle WebLogic; Webcast May 15th 2012 http://wp.me/p1LMIb-gS Andreas Koop? new post ADF Bug or Feature? Non-Breaking Space outside required icon style http://bit.ly/KDZnUo Oracle WebLogic? Don't miss this month's WebLogic DevCast: WebLogic JMS and Spring JMS http://bit.ly/J6g2ST Tuesday May 15th 10:00am PT JDeveloper & ADF How To Disable SELECT COUNT Execution for ADF Table Rendering http://dlvr.it/1dqKH6 OracleSupport_WLS? #SSL and security has its own Information Center, http://bit.ly/LP8Vil for troubleshooting, install, config and more NetBeans Team? Featured #NetBeans plugin is @Codename_One for creating native apps for major mobile platforms: http://plugins.netbeans.org/ JDeveloper & ADF? Using JDeveloper HTTP Analyser to intercept/forward requests http://dlvr.it/1Yzl4J Nicolas Lorain? Create native looks for JavaFX applications: JavaFX-CSS-Themes · http://buff.ly/M0jel0 by Gregg Setzer Devoxx? Want to make the world a better place? Then get involved in Random Hacks of Kindness on June 2 - 3 in Belgium @ http://www.rhok.be #RHoK WebLogic Community top tweets WebLogic Partner Community – May 2012 Click here #WebLogicCommunity Michel Schildmeijer Oracle Traffic Director 11g http://lnkd.in/-mm3Vy Andrejus Baranovskis? Proactively Monitoring JDeveloper 11g IDE Heap Memory http://fb.me/16YZErPrx Arun Gupta? 80+ attendees building a #javaee6 application using NetBeans/WebLogic at Java Day, Istanbul fun times! http://pic.twitter.com/odY19daW A. Chatziantoniou? Just registered for the Oracle FMW Summer Camp in Lisbon. Looking forward to learn, meet friends and try to buy ice cream on the beach OTNArchBeat Another Myth Debunked: 200 Continuous Redeployments with WebLogic|@munz http://bit.ly/JiPyM7 Oracle WebLogic? Need to learn more on #WebLogic Server #JVM performance tuning? http://bit.ly/MN UxHx GlassFish? Dukes Choice Awards 2012 Nominations Are Open: 2012 Duke's Choice Award are open for nominations. These awards http://bit.ly/Ksk4U3 Justin Kestelyn? Major cloud-related announcements from Larry Ellison and Mark Hurd on June 6 http://bit.ly/KTJiII Nicolas Lorain Transparent Windows (Stage) with #JavaFX 2 : Adam Bien's Weblog http://j.mp/INgq8K WebLogic Community Web Services with JAX and Spring on WebLogic–Webcast May 30th 2012 #WebLogicCommunity #weblogic #opn JDeveloper & ADF Oracle ADF - How to work with Dates http://dlvr.it/1Y70zw OracleBlogs Web Services with JAX and Spring on WebLogicWebcast May 30th 2012 http://ow.ly/1k2WtO Adam Bien? Summer Java EE Workshops: 23.05, Amsterdam Airport Java EE Hacking, Without Airport. The dutch version of Airport http://bit.ly/JeP6hV JDeveloper & ADF ADF 11g: BC4J or EJB3. http://bit.ly/JVVFZF ADF EMG? Great discussion with JSF guru Andy Schwartz on the forum - 38 posts! Check it out: here Devoxx? Oracle (http://www.oracle.com ) joins Devoxx 2012 as the first Premium partner, welcome aboard! Nicolas Lorain Developing a Simple Todo Application using #JavaFX, #Java and #MongoDB- Part-1JavaBeat http://j.mp/IDGxLA Nicolas Lorain Preview of JavaFX 2.2 canvas feature > Harmonic Code: Death bitmaps could be beautiful... Part I http://buff.ly/KyAXg5 #JavaFX OTNArchBeat?? New York Coherence Special Interest Group (NYCSIG) - May 24 - NYC http://bit.ly/JzJcbT WebLogic Community iAS upgrade to WebLogic watch #C2B2 online seminar http://youtu.be/5m2CNUjBIGQ #WebLogicCommunity Ruth Collett? Join Oracle in #Joburg on May 21 for OTN Developer Day - sessions on #Java #JavaEE 6/7 and much more! http://bit.ly/IENwnD WebLogic Community? Sending out invitations to our advanced Fusion Middleware Summer Camps! Want to learn more register for the community Ruth Collett? Join @ArunGupta in Istanbul this Monday to hear the latest on #JavaEE 6/7 http://bit.ly/Je63cc GlassFish? NetBeans 7.2 Beta - Built for Speed, Deploy Apps to Oracle Cloud: NetBeans 7.2 Beta is now available. The http://bit.ly/LxMMTK Lucas Jellema My latest SlideShare upload : Java ain't scary - introducing Java to PL/SQ. here via @slideshare JDeveloper & ADF? #Developer #free#ADF training in #Scotland - June 13. More information: http://bit.ly/LbPLlf AMIS, Oracle & Java? AMIS behaalt als eerste in Nedeland de Oracle ADF specialisatie - Channelworld nieuwsChannelconnect: http://bit.ly/JzAcB4 WebLogic Community Web Services with JAX and Spring on WebLogic&ndash;Webcast May 30th 2012 http://wp.me/p1LMIb-gX Nicolas Lorain?@ JavaFX-based SimpleDateFormat Demonstrator http://j.mp/KFCVOi #JavaFX via Dustin Marx Oracle Exalogic? Are you an Oracle partner? There's news on the Oracle Partner Network about #Exalogic specializations - http://bit.ly/Mt3ANY JDeveloper & ADF Shorter URL for your ADF application http://dlvr.it/1XqNLY OTNArchBeat? Bay Area Coherence Special Interest Group (BACSIG) Meeting June 7 http://bit.ly/JAa0Lx OTNArchBeat? Java EE 6 Sample Application on WebLogic 12c: Conference Planner | @arungupta http://bit.ly/LPvof4 JDeveloper & ADF? Excellent example of Oracle ADF - Google Maps/Earth integration http://dlvr.it/1cbc80 JDeveloper & ADF Setting Up JDeveloper's Embedded WLS for MySQL http://dlvr.it/1c4b8P JDeveloper & ADF? Solution for Sharing Global User Data in ADF BC http://dlvr.it/1cc7SJ Java? Java Magazine May/June #javaee #javafx #javame #openJDK #hotspot #wicket #lotsmore http://ow.ly/aX07v Oracle WebLogic? http://bit.ly/JxQsnS if you have trouble finding the right #patchset when doing an upgrade to your #weblogic server OracleEnterpriseMgr 15 minutes to go before we start our Application Testing Suite 12.1 webcast. http://bit.ly/JHyTEe Learn from the lead PM what's new. #em12c Sten Vesterli Eating your own dog food - Oracle support site finally in ADF: http://lnkd.in/s6hg_p Adam Bien Project: "Jenever" (=poison) checked-in with GIT:here CU at http://workshops.adam-bien.com. Thanks for attending! OTNArchBeat Web Service Development with NetBeans and Testing with WebLogic Admin Console | @munz http://bit.ly/JcWk34 Please feel free to send us your news! And add your blog to our SOA blog wiki

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  • Beware Sneaky Reads with Unique Indexes

    - by Paul White NZ
    A few days ago, Sandra Mueller (twitter | blog) asked a question using twitter’s #sqlhelp hash tag: “Might SQL Server retrieve (out-of-row) LOB data from a table, even if the column isn’t referenced in the query?” Leaving aside trivial cases (like selecting a computed column that does reference the LOB data), one might be tempted to say that no, SQL Server does not read data you haven’t asked for.  In general, that’s quite correct; however there are cases where SQL Server might sneakily retrieve a LOB column… Example Table Here’s a T-SQL script to create that table and populate it with 1,000 rows: CREATE TABLE dbo.LOBtest ( pk INTEGER IDENTITY NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( some_value, lob_data ) SELECT TOP (1000) N.n, @Data FROM Numbers N WHERE N.n <= 1000; Test 1: A Simple Update Let’s run a query to subtract one from every value in the some_value column: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; As you might expect, modifying this integer column in 1,000 rows doesn’t take very long, or use many resources.  The STATITICS IO and TIME output shows a total of 9 logical reads, and 25ms elapsed time.  The query plan is also very simple: Looking at the Clustered Index Scan, we can see that SQL Server only retrieves the pk and some_value columns during the scan: The pk column is needed by the Clustered Index Update operator to uniquely identify the row that is being changed.  The some_value column is used by the Compute Scalar to calculate the new value.  (In case you are wondering what the Top operator is for, it is used to enforce SET ROWCOUNT). Test 2: Simple Update with an Index Now let’s create a nonclustered index keyed on the some_value column, with lob_data as an included column: CREATE NONCLUSTERED INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); This is not a useful index for our simple update query; imagine that someone else created it for a different purpose.  Let’s run our update query again: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; We find that it now requires 4,014 logical reads and the elapsed query time has increased to around 100ms.  The extra logical reads (4 per row) are an expected consequence of maintaining the nonclustered index. The query plan is very similar to before (click to enlarge): The Clustered Index Update operator picks up the extra work of maintaining the nonclustered index. The new Compute Scalar operators detect whether the value in the some_value column has actually been changed by the update.  SQL Server may be able to skip maintaining the nonclustered index if the value hasn’t changed (see my previous post on non-updating updates for details).  Our simple query does change the value of some_data in every row, so this optimization doesn’t add any value in this specific case. The output list of columns from the Clustered Index Scan hasn’t changed from the one shown previously: SQL Server still just reads the pk and some_data columns.  Cool. Overall then, adding the nonclustered index hasn’t had any startling effects, and the LOB column data still isn’t being read from the table.  Let’s see what happens if we make the nonclustered index unique. Test 3: Simple Update with a Unique Index Here’s the script to create a new unique index, and drop the old one: CREATE UNIQUE NONCLUSTERED INDEX [UQ dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); GO DROP INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest; Remember that SQL Server only enforces uniqueness on index keys (the some_data column).  The lob_data column is simply stored at the leaf-level of the non-clustered index.  With that in mind, we might expect this change to make very little difference.  Let’s see: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; Whoa!  Now look at the elapsed time and logical reads: Scan count 1, logical reads 2016, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   CPU time = 172 ms, elapsed time = 16172 ms. Even with all the data and index pages in memory, the query took over 16 seconds to update just 1,000 rows, performing over 52,000 LOB logical reads (nearly 16,000 of those using read-ahead). Why on earth is SQL Server reading LOB data in a query that only updates a single integer column? The Query Plan The query plan for test 3 looks a bit more complex than before: In fact, the bottom level is exactly the same as we saw with the non-unique index.  The top level has heaps of new stuff though, which I’ll come to in a moment. You might be expecting to find that the Clustered Index Scan is now reading the lob_data column (for some reason).  After all, we need to explain where all the LOB logical reads are coming from.  Sadly, when we look at the properties of the Clustered Index Scan, we see exactly the same as before: SQL Server is still only reading the pk and some_value columns – so what’s doing the LOB reads? Updates that Sneakily Read Data We have to go as far as the Clustered Index Update operator before we see LOB data in the output list: [Expr1020] is a bit flag added by an earlier Compute Scalar.  It is set true if the some_value column has not been changed (part of the non-updating updates optimization I mentioned earlier). The Clustered Index Update operator adds two new columns: the lob_data column, and some_value_OLD.  The some_value_OLD column, as the name suggests, is the pre-update value of the some_value column.  At this point, the clustered index has already been updated with the new value, but we haven’t touched the nonclustered index yet. An interesting observation here is that the Clustered Index Update operator can read a column into the data flow as part of its update operation.  SQL Server could have read the LOB data as part of the initial Clustered Index Scan, but that would mean carrying the data through all the operations that occur prior to the Clustered Index Update.  The server knows it will have to go back to the clustered index row to update it, so it delays reading the LOB data until then.  Sneaky! Why the LOB Data Is Needed This is all very interesting (I hope), but why is SQL Server reading the LOB data?  For that matter, why does it need to pass the pre-update value of the some_value column out of the Clustered Index Update? The answer relates to the top row of the query plan for test 3.  I’ll reproduce it here for convenience: Notice that this is a wide (per-index) update plan.  SQL Server used a narrow (per-row) update plan in test 2, where the Clustered Index Update took care of maintaining the nonclustered index too.  I’ll talk more about this difference shortly. The Split/Sort/Collapse combination is an optimization, which aims to make per-index update plans more efficient.  It does this by breaking each update into a delete/insert pair, reordering the operations, removing any redundant operations, and finally applying the net effect of all the changes to the nonclustered index. Imagine we had a unique index which currently holds three rows with the values 1, 2, and 3.  If we run a query that adds 1 to each row value, we would end up with values 2, 3, and 4.  The net effect of all the changes is the same as if we simply deleted the value 1, and added a new value 4. By applying net changes, SQL Server can also avoid false unique-key violations.  If we tried to immediately update the value 1 to a 2, it would conflict with the existing value 2 (which would soon be updated to 3 of course) and the query would fail.  You might argue that SQL Server could avoid the uniqueness violation by starting with the highest value (3) and working down.  That’s fine, but it’s not possible to generalize this logic to work with every possible update query. SQL Server has to use a wide update plan if it sees any risk of false uniqueness violations.  It’s worth noting that the logic SQL Server uses to detect whether these violations are possible has definite limits.  As a result, you will often receive a wide update plan, even when you can see that no violations are possible. Another benefit of this optimization is that it includes a sort on the index key as part of its work.  Processing the index changes in index key order promotes sequential I/O against the nonclustered index. A side-effect of all this is that the net changes might include one or more inserts.  In order to insert a new row in the index, SQL Server obviously needs all the columns – the key column and the included LOB column.  This is the reason SQL Server reads the LOB data as part of the Clustered Index Update. In addition, the some_value_OLD column is required by the Split operator (it turns updates into delete/insert pairs).  In order to generate the correct index key delete operation, it needs the old key value. The irony is that in this case the Split/Sort/Collapse optimization is anything but.  Reading all that LOB data is extremely expensive, so it is sad that the current version of SQL Server has no way to avoid it. Finally, for completeness, I should mention that the Filter operator is there to filter out the non-updating updates. Beating the Set-Based Update with a Cursor One situation where SQL Server can see that false unique-key violations aren’t possible is where it can guarantee that only one row is being updated.  Armed with this knowledge, we can write a cursor (or the WHILE-loop equivalent) that updates one row at a time, and so avoids reading the LOB data: SET NOCOUNT ON; SET STATISTICS XML, IO, TIME OFF;   DECLARE @PK INTEGER, @StartTime DATETIME; SET @StartTime = GETUTCDATE();   DECLARE curUpdate CURSOR LOCAL FORWARD_ONLY KEYSET SCROLL_LOCKS FOR SELECT L.pk FROM LOBtest L ORDER BY L.pk ASC;   OPEN curUpdate;   WHILE (1 = 1) BEGIN FETCH NEXT FROM curUpdate INTO @PK;   IF @@FETCH_STATUS = -1 BREAK; IF @@FETCH_STATUS = -2 CONTINUE;   UPDATE dbo.LOBtest SET some_value = some_value - 1 WHERE CURRENT OF curUpdate; END;   CLOSE curUpdate; DEALLOCATE curUpdate;   SELECT DATEDIFF(MILLISECOND, @StartTime, GETUTCDATE()); That completes the update in 1280 milliseconds (remember test 3 took over 16 seconds!) I used the WHERE CURRENT OF syntax there and a KEYSET cursor, just for the fun of it.  One could just as well use a WHERE clause that specified the primary key value instead. Clustered Indexes A clustered index is the ultimate index with included columns: all non-key columns are included columns in a clustered index.  Let’s re-create the test table and data with an updatable primary key, and without any non-clustered indexes: IF OBJECT_ID(N'dbo.LOBtest', N'U') IS NOT NULL DROP TABLE dbo.LOBtest; GO CREATE TABLE dbo.LOBtest ( pk INTEGER NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( pk, some_value, lob_data ) SELECT TOP (1000) N.n, N.n, @Data FROM Numbers N WHERE N.n <= 1000; Now here’s a query to modify the cluster keys: UPDATE dbo.LOBtest SET pk = pk + 1; The query plan is: As you can see, the Split/Sort/Collapse optimization is present, and we also gain an Eager Table Spool, for Halloween protection.  In addition, SQL Server now has no choice but to read the LOB data in the Clustered Index Scan: The performance is not great, as you might expect (even though there is no non-clustered index to maintain): Table 'LOBtest'. Scan count 1, logical reads 2011, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   Table 'Worktable'. Scan count 1, logical reads 2040, physical reads 0, read-ahead reads 0, lob logical reads 34000, lob physical reads 0, lob read-ahead reads 8000.   SQL Server Execution Times: CPU time = 483 ms, elapsed time = 17884 ms. Notice how the LOB data is read twice: once from the Clustered Index Scan, and again from the work table in tempdb used by the Eager Spool. If you try the same test with a non-unique clustered index (rather than a primary key), you’ll get a much more efficient plan that just passes the cluster key (including uniqueifier) around (no LOB data or other non-key columns): A unique non-clustered index (on a heap) works well too: Both those queries complete in a few tens of milliseconds, with no LOB reads, and just a few thousand logical reads.  (In fact the heap is rather more efficient). There are lots more fun combinations to try that I don’t have space for here. Final Thoughts The behaviour shown in this post is not limited to LOB data by any means.  If the conditions are met, any unique index that has included columns can produce similar behaviour – something to bear in mind when adding large INCLUDE columns to achieve covering queries, perhaps. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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  • Understanding C# async / await (1) Compilation

    - by Dixin
    Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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  • Understanding C# async / await (1) Compilation

    - by Dixin
    Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification  can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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  • ColdFusion Server crash after thousands of HTTP requests

    - by Jason Bristol
    We are running ColdFusion 8 on a windows server 2003 VPS with an API that exposes student records to a partner API through a connector. Our API returns around 50k student records serialized in XML format pretty seamlessly. My question originates when something very frightening happened today when we tested our connector to our partners API. Our entire website and web host went down. We assumed that our host was just having some issues and after 4 hours with no resolution and no response from their customer service we finally got a response from them claiming that they had an "unauthorized user" in their network. After our server was back up we were unable to connect to our website as if the web service or coldfusion itself had froze. This is really where my concern comes from as I fear we may have overloaded the web service. As I mentioned before we tried sending over 50k HTTP POST requests over to our partner's API, however everything stopped after around 1.6k Is this bad practice or is there some sort of rate limiting I can relax somewhere in server configuration? We managed to find a workaround, but it bypasses our connector which is critical to our design. This would have been a one time deal as the purpose of so many requests was to populate our partner's website with current data, after that hourly syncs will keep requests down to around 100 per hour. UPDATE Our partner API is owned and operated by Pardot. We are converting students to prospects by passing student data to their API which unfortunately only seems to accept one student at a time. For that reason we have to do all 50k requests individually. Our server has 4GB of RAM, an Intel Core 2 Duo @ 2.8GHz running Windows Server 2003 SP2. I monitored the server during a 100 student sync, a 400 student sync, and a 1.4k student sync with the following results: 100 students - 2.25GB of Memory, 30-40% CPU utilization, 0.2-0.3% network bandwidth 400 students - 2.30GB of Memory, 30-50% CPU utilization, 0.2-1.0% network bandwidth 1.4k students - 2.30GB of Memory, 30-70% CPU utilization, 0.2-1.0% network bandwidth I know this is a far cry from 50k students, but I don't want to risk taking down our CMS system again assuming that was the cause. To give you a look at our code: <cfif (#getStudents.statusCode# eq "200 OK")> <cftry> <cfloop index="StudentXML" array="#XmlSearch(responseSTUD,'/students/student')#"> <cfset StudentXML = XmlParse(StudentXML)> <cfhttp url="#PARDOT_CMS_UPSERT#" method="post" timeout="10000" > <cfhttpparam type="url" name="user_key" value="#PARDOT_CMS_USERKEY#"> <cfhttpparam type="url" name="api_key" value="#api_key#"> <cfhttpparam type="url" name="email" value="#StudentXML.student.email.XmlText#"> <cfhttpparam type="url" name="first_name" value="#StudentXML.student.first.XmlText#"> <cfhttpparam type="url" name="last_name" value="#StudentXML.student.last.XmlText#"> <cfhttpparam type="url" name="in_cms" value="#StudentXML.student.studentid.XmlText#"> <cfhttpparam type="url" name="company" value="#StudentXML.student.agencyname.XmlText#"> <cfhttpparam type="url" name="country" value="#StudentXML.student.countryname.XmlText#"> <cfhttpparam type="url" name="address_one" value="#StudentXML.student.address.XmlText#"> <cfhttpparam type="url" name="address_two" value="#StudentXML.student.address2.XmlText#"> <cfhttpparam type="url" name="city" value="#StudentXML.student.city.XmlText#"> <cfhttpparam type="url" name="state" value="#StudentXML.student.state_province.XmlText#"> <cfhttpparam type="url" name="zip" value="#StudentXML.student.postalcode.XmlText#"> <cfhttpparam type="url" name="phone" value="#StudentXML.student.phone.XmlText#"> <cfhttpparam type="url" name="fax" value="#StudentXML.student.fax.XmlText#"> <cfhttpparam type="url" name="output" value="simple"> </cfhttp> </cfloop> <cfcatch type="any"> <cfdump var="#cfcatch.Message#"> </cfcatch> </cftry> </cfif> UPDATE 2 I checked the CF logs and found a couple of these: "Error","jrpp-8","06/06/13","16:10:18","CMS-API","Java heap space The specific sequence of files included or processed is: D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm, line: 675 " java.lang.OutOfMemoryError: Java heap space at java.util.Arrays.copyOf(Arrays.java:2882) at java.io.CharArrayWriter.write(CharArrayWriter.java:105) at coldfusion.runtime.CharBuffer.replace(CharBuffer.java:37) at coldfusion.runtime.CharBuffer.replace(CharBuffer.java:50) at coldfusion.runtime.NeoBodyContent.write(NeoBodyContent.java:254) at cfapi2ecfm292155732._factor30(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:675) at cfapi2ecfm292155732._factor31(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:662) at cfapi2ecfm292155732._factor36(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:659) at cfapi2ecfm292155732._factor42(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:657) at cfapi2ecfm292155732._factor37(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm) at cfapi2ecfm292155732._factor44(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:456) at cfapi2ecfm292155732._factor38(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm) at cfapi2ecfm292155732._factor46(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:455) at cfapi2ecfm292155732._factor39(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm) at cfapi2ecfm292155732._factor47(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:453) at cfapi2ecfm292155732.runPage(D:\Clients\www.xxx.com\www\dev.cms\api\v1\api.cfm:1) at coldfusion.runtime.CfJspPage.invoke(CfJspPage.java:192) at coldfusion.tagext.lang.IncludeTag.doStartTag(IncludeTag.java:366) at coldfusion.filter.CfincludeFilter.invoke(CfincludeFilter.java:65) at coldfusion.filter.ApplicationFilter.invoke(ApplicationFilter.java:279) at coldfusion.filter.RequestMonitorFilter.invoke(RequestMonitorFilter.java:48) at coldfusion.filter.MonitoringFilter.invoke(MonitoringFilter.java:40) at coldfusion.filter.PathFilter.invoke(PathFilter.java:86) at coldfusion.filter.ExceptionFilter.invoke(ExceptionFilter.java:70) at coldfusion.filter.ClientScopePersistenceFilter.invoke(ClientScopePersistenceFilter.java:28) at coldfusion.filter.BrowserFilter.invoke(BrowserFilter.java:38) at coldfusion.filter.NoCacheFilter.invoke(NoCacheFilter.java:46) at coldfusion.filter.GlobalsFilter.invoke(GlobalsFilter.java:38) at coldfusion.filter.DatasourceFilter.invoke(DatasourceFilter.java:22) at coldfusion.CfmServlet.service(CfmServlet.java:175) at coldfusion.bootstrap.BootstrapServlet.service(BootstrapServlet.java:89) at jrun.servlet.FilterChain.doFilter(FilterChain.java:86) Looks like I might have crashed the JVM in CF, is there a better way to do this? We are thinking of just exporting all records initially as a CSV file and importing it into Pardot seeing as we will never have to do a request this large again.

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  • OutOfMemoryException - out of ideas II

    - by Captain Comic
    Hello, This question is related to my previous question. The storyline: I have an application which consumes a lot of memory if you look at task manager VMSize. I am trying to find out what consumes this amount of memory. You see in the picture below that VM size is 2,46 GB Ok now I am looking at .net performance counters Committed and reserved bytes add up to only 1,2 GB Now lets look at windb sos debugging. Let's run eeheap -gc command The heap size used by GC is only 340 MB. Where is the rest of used memory? I need to discover why WM size in TaskManager is 2.4 GB

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  • Android: Strange out of memory issue

    - by Chrispix
    I am not sure where to start to explain this one. I have a list view with a couple image buttons on each row. When you click the list row, it launches a new activity. If you review some of my other posts, I have had to build my own tabs because of an issue w/ the camera layout. The activity that gets launched for result is a map. If I click on my button to launch the image preview (load an image off the sd card) the application returns from the activity back to the listview activity to the result handler to relaunch my new activity which is nothing more than an image widget. So here is the issue, the image preview on the list view is being done w/ the cursor & listadapter. This makes it pretty simple, but I am not sure how I can put a resized (i.e. smaller bit size not pixel) image as the src for the imgbutton on the fly. So I just resized the image that came off the phone camera. The issue is that I get an out of memory error when it tries to go back and re-launch the 2nd activity. ** My question : is there a way I can build the list adapter easily row by row, where I can resize on the fly (bit wise)? - this would be preferable as I also need to make some changes to the properties of the widgets/elements in each row as I am unable to select a row w/ touch screen b/c of focus issue. (I can use roller ball). ** I know I can do an out of band resize and save of my image, but that is not really what I want to do, but some sample code for that would be nice if that is your suggestion. As soon as I disabled the image on the listview it worked fine again. FYI : This is how I was doing it : String[] from = new String[] { DBHelper.KEY_BUSINESSNAME, DBHelper.KEY_ADDRESS, DBHelper.KEY_CITY, DBHelper.KEY_GPSLONG, DBHelper.KEY_GPSLAT, DBHelper.KEY_IMAGEFILENAME + ""}; to = new int[] { R.id.businessname, R.id.address, R.id.city, R.id.gpslong, R.id.gpslat, R.id.imagefilename }; notes = new SimpleCursorAdapter(this, R.layout.notes_row, c, from, to); setListAdapter(notes); Where R.id.imagefilename is a ButtonImage Here is my LogCat 01-25 05:05:49.877: ERROR/dalvikvm-heap(3896): 6291456-byte external allocation too large for this process. 01-25 05:05:49.877: ERROR/(3896): VM won't let us allocate 6291456 bytes 01-25 05:05:49.877: ERROR/AndroidRuntime(3896): Uncaught handler: thread main exiting due to uncaught exception 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): java.lang.OutOfMemoryError: bitmap size exceeds VM budget 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.nativeDecodeStream(Native Method) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.decodeStream(BitmapFactory.java:304) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:149) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.BitmapFactory.decodeFile(BitmapFactory.java:174) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.graphics.drawable.Drawable.createFromPath(Drawable.java:729) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ImageView.resolveUri(ImageView.java:484) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ImageView.setImageURI(ImageView.java:281) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.SimpleCursorAdapter.setViewImage(SimpleCursorAdapter.java:183) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.SimpleCursorAdapter.bindView(SimpleCursorAdapter.java:129) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.CursorAdapter.getView(CursorAdapter.java:150) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.AbsListView.obtainView(AbsListView.java:1057) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ListView.makeAndAddView(ListView.java:1616) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ListView.fillSpecific(ListView.java:1177) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.ListView.layoutChildren(ListView.java:1454) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.AbsListView.onLayout(AbsListView.java:937) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1108) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.onLayout(LinearLayout.java:922) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.FrameLayout.onLayout(FrameLayout.java:294) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:999) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.LinearLayout.onLayout(LinearLayout.java:920) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.widget.FrameLayout.onLayout(FrameLayout.java:294) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.View.layout(View.java:5611) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.ViewRoot.performTraversals(ViewRoot.java:771) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.view.ViewRoot.handleMessage(ViewRoot.java:1103) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.os.Handler.dispatchMessage(Handler.java:88) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.os.Looper.loop(Looper.java:123) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at android.app.ActivityThread.main(ActivityThread.java:3742) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at java.lang.reflect.Method.invokeNative(Native Method) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at java.lang.reflect.Method.invoke(Method.java:515) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:739) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:497) 01-25 05:05:49.917: ERROR/AndroidRuntime(3896): at dalvik.system.NativeStart.main(Native Method) 01-25 05:10:01.127: ERROR/AndroidRuntime(3943): ERROR: thread attach failed I also have a new error when displaying an image : 01-25 22:13:18.594: DEBUG/skia(4204): xxxxxxxxxxx jpeg error 20 Improper call to JPEG library in state %d 01-25 22:13:18.604: INFO/System.out(4204): resolveUri failed on bad bitmap uri: 01-25 22:13:18.694: ERROR/dalvikvm-heap(4204): 6291456-byte external allocation too large for this process. 01-25 22:13:18.694: ERROR/(4204): VM won't let us allocate 6291456 bytes 01-25 22:13:18.694: DEBUG/skia(4204): xxxxxxxxxxxxxxxxxxxx allocPixelRef failed

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  • the scope of a pointer ???

    - by numerical25
    Ok, so I did find some questions that were almost similar but they actually confused me even more about pointers. http://stackoverflow.com/questions/2715198/c-pointer-objects-vs-non-pointer-objects-closed In the link above, they say that if you declare a pointer it is actually saved on the heap and not on the stack, regardless of where it was declared at. Is this true ?? Or am I misunderstanding ??? I thought that regardless of a pointer or non pointer, if its a global variable, it lives as long as the application. If its a local variable or declared within a loop or function, its life is only as long as the code within it.

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  • stanford pos tagger runs out of memory?

    - by goh
    my stanford tagger ran out of memory. Is it because the text has to be properly formatted? This is because i use it to tag html contents, with the tags stripped, but there may have quite a excessive amount of newlines. here is the error: BlockquoWARNING: Untokenizable: ? (char in decimal: 9829) Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at edu.stanford.nlp.sequences.ExactBestSequenceFinder.bestSequenceNew(Ex actBestSequenceFinder.java:175) at edu.stanford.nlp.sequences.ExactBestSequenceFinder.bestSequence(Exact BestSequenceFinder.java:98) at edu.stanford.nlp.tagger.maxent.TestSentence.runTagInference(TestSente nce.java:277) at edu.stanford.nlp.tagger.maxent.TestSentence.testTagInference(TestSent ence.java:258) at edu.stanford.nlp.tagger.maxent.TestSentence.tagSentence(TestSentence. java:110) at edu.stanford.nlp.tagger.maxent.MaxentTagger.tagSentence(MaxentTagger. java:825) at edu.stanford.nlp.tagger.maxent.MaxentTagger.runTagger(MaxentTagger.ja va:1319) at edu.stanford.nlp.tagger.maxent.MaxentTagger.runTagger(MaxentTagger.ja va:1225) at edu.stanford.nlp.tagger.maxent.MaxentTagger.runTagger(MaxentTagger.ja va:1183) at edu.stanford.nlp.tagger.maxent.MaxentTagger.main(MaxentTagger.java:13 58)

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  • NedMalloc / DlMalloc experiences

    - by Suma
    I am currently evaluating a few of scalable memory allocators, namely nedmalloc and ptmalloc (both built on top of dlmalloc), as a replacement for default malloc / new because of significant contention seen in multithreaded environment. Their published performance seems to be good, however I would like to check what are experiences of other people who have really used them. Were your performance goals satisfied? Did you experience any unexpected or hard to solve issues (like heap corruption)? If you have tried both ptmaalloc and nedmalloc, which of the two would you recommend? Why (ease of use, performance)?

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  • Split textarea content into two at maxlength and flow excedant content in another textarea

    - by user1057339
    Wondering if its possible to create a short simple and sweet cross-browser jQuery (1.6) function that would split #textarea1 content into two by preserving the characters that amount to less than its var maxlength limit and transfering the remaining characters that exceed its maxlength limit in #textarea2. #textarea1 can push excedant in #textarea2, but if #textarea1 contains less than the maxlength limit, by default it wont get filled up with #textarea2 content, but you would have the option programatically to override this. I am just beginning to scratch the surface of jQuery but I noticed that this simple javascript can nearly do the trick, minus the free-flowing character movement. Scratching my head on this one. Thx a heap for any help. DC

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  • What causes a JRE 6 JVM code cache leak?

    - by Arturo Knight
    Since switching to JRE 6, my server's code cache usage (non-heap) keeps growing indefinitely. My application creates a lot of classes at runtime, BUT these classes are successfully unloaded during the GC process. I can see these classes getting unloaded in the gc logs and also the permGen usage stays constant. I specifically make sure in my code that these classes are orphaned once I am finished with them and so they correctly get garbage collected from permGen. The code cache however keeps growing. I only became aware of the code cache after switching to JRE 6. So I guess my questions are: Does GC include the code cache? What could cause a code cache memory leak, specifically. Is there a bug in JDK 6 in this area?

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  • Decoding bitmaps in Android with the right size

    - by hgpc
    I decode bitmaps from the SD card using BitmapFactory.decodeFile. Sometimes the bitmaps are bigger than what the application needs or that the heap allows, so I use BitmapFactory.Options.inSampleSize to request a subsampled (smaller) bitmap. The problem is that the platform does not enforce the exact value of inSampleSize, and I sometimes end up with a bitmap either too small, or still too big for the available memory. From http://developer.android.com/reference/android/graphics/BitmapFactory.Options.html#inSampleSize: Note: the decoder will try to fulfill this request, but the resulting bitmap may have different dimensions that precisely what has been requested. Also, powers of 2 are often faster/easier for the decoder to honor. How should I decode bitmaps from the SD card to get a bitmap of the exact size I need while consuming as little memory as possible to decode it?

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