c# - async and await code behaving differently if we run it from different processes -


please bear me long question.

scenario: have filesystemwatcher on root-directory watching lastwrite change on control-file each inside control-directory. looks this:-

root-directory (filesystemwatcher instance watching root directory)

|

|-----control-directory_0 \ control-file

                      \ data-file

|-----control-directory_1 \ control-file

                      \ data-file

|-----control-directory_2 \ control-file

                      \ data-file

|-----control-directory_3 \ control-file

                      \ data-file

.........more similar structure (but 1 root-directory)

sorry creative drawing.

the problem facing, there can many control-directories inside root-directory (approx 200-500) , along control-directory's control-file, have data-file in (in each of them) continuous writes happening.

i watching notifyfilter.lastwrite , filter = control-file. internalbuffersize set 4kb (please don't ask increase this, not allowed modify , event make 8kb (default one) due requirements , can't use filesystemwatcher each control-file take lot of precious non-paged memory).

my eventhandler looks this

  private void onchange(object sender, filesystemeventargs eventargs)   {      //result = cpu bound work here      //evaluating result   }

currently, handling 300 control-files. due lots of writes happening on data-file , lots of requests coming control-file buffer overflowing quite regularly.

then thought of idea. (async , await rescue task battle tank)

  async private void onchange(object sender, filesystemeventargs eventargs)   {      var result = await task.run(() => work.cpuboundwork());      //evaluating result   }

it working fine , able handle lots of requests (even tested 1000 events 4kb buffer).

now comes interesting part. how testing it?

there 2 entities involved, one, writing control or data-file , second, handling events generated writes control-file. went , created console app, both of things.

static void main(string[] args) {   int controlfilecount = convert.toint32(args[0]);   string basepath = args[1];   //createfolderstructure(basepath, controlfilecount); first run.   filesystemwatcher basedirectorywatcher = new filesystemwatcher();   setupfilesystemwatcher(basedirectorywatcher, basepath);   writetocontrolfilesparallely(basepath, controlfilecount);   console.read(); }  public void setupfilesystemwatcher(filesystemwatcher basedirectorywatcher, string path) {   //setting properties of watcher.   basedirectorywatcher.notifyfilter = notifyfilter.lastwrite;   basedirectorywatcher.filter = "control-file";   basedirectorywatcher.internalbuffersize = 4096;   basedirectorywatcher.path = path;   basedirectorywatcher.includesubdirectories = true;   basedirectorywatcher.enableraisingevents = true; }  public void writetocontrolfilesparallely(string basepath, int controlfilecount) {   parallel.for(0, controlfilecount, (i) =>   {     string filepath = helper.getfilepath(basepath, i);     helper.writedata(filepath, "data");   }); }

next, tested 2 console applications:-

first, responsible of writing data various control files parallelly - (writer_app).

second, responsible handling events - (event_handling_app).

note: there's no code change in core instead of writing , handling events in same console app writing 1 , handling form other.

so separated 2 entities old console app (starting simulation actual environment). started testing running first event_handling_app , write control-file running writer_app , things have become strange , application facing internalbufferoverflow exception same number of control-files , same number of writes when didn't have async , await in first implementation.

i again tested 1 console app (which having both responsibilities) , working fine.

so, why 2 console applications make magic of async , await (along task) disappear while 1 console application working great?

is related inter process communication?

i wondering if work in production because using handler code in web application , other process can write these files on network.

finally, able figure out this, when using single console app running exe (through cmd) when trying 2 console app running app inside visual studio (in release mode) due (with load of visual studio) getting exception , blaming async , await.

so, run application exe if dealing code tight.


Comments

Post a Comment

Popular posts from this blog

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m
Read more

python Tkinter Capturing keyboard events save as one single string -

is possible store keyboard events 1 string? code below stores 1 char , prints it. card reader or bar code reader, contains collection of character/ string not 1 character @ time. goal save char pressed text variable. from tkinter import * root = tk() def key(event): text= event.char text+= event.char print ("pressed", text) def callback(event): frame.focus_set() print ("clicked at", event.x, event.y) frame = frame(root, width=100, height=100) frame.bind("<key>", key) frame.bind("<button-1>", callback) frame.pack() root.mainloop() currently, creating text variable , everytime key() function gets called, , text stores last character typed. you can define text module level variable , , use module level text inside key function - text = '' def key(event): global text text+= event.char print("pressed", text)
Read more

sql server - Why does Linq-to-SQL add unnecessary COUNT()? -

here tables: create table customer ( cid int primary key, name varchar(32) ) create table ord ( oid int primary key, cid int foreign key references customer, address varchar(20) ) here's linq-to-sql statement: var aaa = c in db.customer select new { c, o = c.ord.tolist() }; and here's inexplicable query generated linq-to-sql: select [t0].[cid] [cid], [t0].[name] [name], [t1].[oid] [oid], [t1].[cid] [cid2], [t1].[address] [address], (select count(*) [dbo].[ord] [t2] [t2].[cid] = [t0].[cid]) [value] [dbo].[customer] [t0] left outer join [dbo].[ord] [t1] on [t1].[cid] = [t0].[cid] order [t0].[cid], [t1].[oid] i want understand how rid of count(*) part. it's entirely uncalled for! linq needs count(*) in order determine number of entries returned o = c.ord.tolist() .
Read more