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ios – Why doesn’t calling serialQueue.sync() end in a impasse?


Whereas finding out DispatchQueue, I got here throughout one thing I don’t fairly perceive.

I created a customized serial queue and executed a synchronous block on it. After I printed the thread that was working the block, it turned out to be the principle thread. This confused me, as a result of the queue wasn’t the principle queue, but the block nonetheless executed on the principle thread.

let serialQueue = DispatchQueue(label: "serial.queue")

serialQueue.sync {
    print("present thread = (Thread.present)") // present thread = _NSMainThread
}

Within the documentation for sync(), I discovered the next assertion:

As a efficiency optimization, this perform executes blocks on the
present thread at any time when attainable, with one exception: Blocks submitted
to the principle dispatch queue all the time run on the principle thread.

Primarily based on this description, I assumed that if the block was certainly executed on the present thread (the principle thread on this case), then a impasse ought to have occurred.

Right here’s the reasoning I had:

  1. The primary thread calls serialQueue.sync(). As a result of it’s synchronous, the principle thread turns into blocked till the block completes.
  2. The block is submitted to the serial queue, which then makes an attempt to execute it on the principle thread (the present thread).
  3. Nevertheless, because the essential thread is already blocked, it wouldn’t be capable to course of the duty, which ought to trigger a impasse.

However opposite to my expectation, no impasse occurred and the code executed simply high-quality. I can’t work out why.

Query.

  1. Why is a block executed on the principle thread though it was submitted to a customized serial queue?
  2. If, because the documentation suggests, sync() executes on the present thread as an optimization, why doesn’t this result in a impasse on this case?
  3. Can the principle thread nonetheless execute different duties whereas it’s blocked? I want to perceive how precisely the principle thread operates.

Chemists rethink plastic recycling – NanoApps Medical – Official web site


What if recycling plastics have been so simple as flicking a change? At TU/e, Assistant Professor Fabian Eisenreich is making that imaginative and prescient a actuality by utilizing LED gentle to each create and break down a brand new class of high-performance plastics. This revolutionary materials allows really round recycling, as this course of might be repeated time and again, with none loss in high quality.

This analysis, revealed within the Rising Stars version of Superior Supplies, marks a breakthrough in  and will reshape how we deal with plastic waste sooner or later.

“In actual fact, we’re molecular designers,” is how Eisenreich describes himself and his fellow scientists from the Polymer Efficiency Supplies analysis group. Of their labs on the Division of Chemical Engineering and Chemistry, that’s what the main target is on.

“Our line of analysis facilities on ‘design for recycling.’ We create new polymers to allow revolutionary recycling methods for plastics. On the identical time, we use natural (bio-based) supplies, keep away from poisonous substances, and reduce waste to maintain all the course of as sustainable as attainable.”

High quality of polymer chains deteriorates

These polymers are developed to allow chemical closed-loop recycling, the last word aim of the analysis group. “Plastics usually include moldable polymer chains. Because of the present method by which plastics are normally recycled—in a nutshell: heating, melting, and reshaping—the standard of these polymer chains deteriorates over time. So you’ll be able to’t hold doing that indefinitely, which signifies that new plastic will ultimately must be made anyway.”

Chemical closed-loop recycling is subsequently the perfect various, in response to Eisenreich. “With the proper chemical response, a polymer chain might be selectively damaged down into its authentic constructing blocks. These can then be reused to make precisely the identical polymer once more, with similar properties and high quality.” Attaining this requires polymers designed to endure that exact response—therefore the main target of the Polymer Efficiency Supplies group’s analysis.

Selectively splitting a polymer with gentle

Inside that context, Eisenreich specifies his personal analysis on photochemical recycling, powered by LED gentle. “Making polymers by the use of gentle is comparatively easy. However breaking and making them once more in the identical method, aka recycling, is far more difficult and subsequently a complete new line of analysis. The problem lies in utilizing gentle to selectively break up steady chemical bonds throughout the polymer, so the unique constructing blocks might be recovered.”

Lately, Eisenreich and Ahsen Sare Yalin, a third-year Ph.D. candidate in his group, turned the primary to efficiently pull off this trick in his lab.

Reshape the best way we cope with plastic waste

“We see it as a breakthrough in sustainable chemistry that may reshape the best way we cope with plastic waste sooner or later,” says Eisenreich. “In the intervening time, our designer polymer continues to be a distinct segment materials and subsequently not appropriate for on a regular basis plastic purposes. As an alternative, it’s geared toward specialised makes use of, for instance, as a recyclable adhesive that binds strongly to glass and different plastics.”

In the end, additional improvement ought to broaden the appliance prospects. Furthermore, Eisenreich sees loads of potential in closed-loop recycling expertise with gentle. “I additionally work on 3D printing recyclable polymers utilizing gentle, which is a really fascinating course of. You begin with a liquid materials that takes on a stable type as quickly as gentle falls on it. You should utilize this course of to print advanced 3D objects.”

His aim is to at some point notice photochemical recycling of conventional plastics with solely daylight. “Then you definitely don’t want another vitality supply, how cool would that be?” Eisenreich’s chemical breakthrough is subsequently not solely shining new gentle on plastic recycling, but in addition on his whole discipline. “This isn’t only a new materials. It’s a brand new method ahead.”

Extra info: Ahsen Sare Yalin et al, A Mild‐Pushed Closed‐Loop Chemical Recycling System for Polypinacols, Superior Supplies (2025). DOI: 10.1002/adma.202506733

policing – Juniper MX and never working policer with NAT service


I’ve a Juniper MX wherte I have to do a community translation and bandwidth policing in the identical time. I’ve tried each approaches – direct policing of a logical interface and a policer inside a firewall filter and in each circumstances output policing would not occur (netspeed take a look at on a bunch in vlan 207 reveals incoming pace of 500 Mbits/sec, add reveals 80 Mbit/secs):

direct policing:

[show interfaces ge-1/0/0 unit 207]
vlan-id 207;
household inet {
    filter {
        output deny-rfc1918-and-allow-some;
    }
    policer {
        enter 80m-30.6m-discard;
        output 80m-30.6m-discard;
    }
    service {
        enter {
            service-set nat-lan;
        }
        output {
            service-set nat-lan-portforward service-filter nat-lan-filter;
            service-set nat-lan;
        }
    }
    tackle 172.16.25.9/29;
}
[show firewall policer 80m-30.6m-discard]
logical-interface-policer;
if-exceeding {
    bandwidth-limit 80m;
    burst-size-limit 30720000;
}
then discard;

policing inside a firewall filter:

[show interfaces ge-1/0/0 unit 207]
vlan-id 207;
household inet {
    filter {
        output deny-rfc1918-and-allow-some-shape-to-80m;
    }
    policer {
        enter 80m-30.6m-discard;
    }
    service {
        enter {
            service-set nat-lan;
        }
        output {
            service-set nat-lan-portforward service-filter nat-lan-filter;
            service-set nat-lan;
        }
    }
    tackle 172.16.25.9/29;
}
[show firewall filter deny-rfc1918-and-allow-some-shape-to-80m]
time period allow-some-and-shape-to-80m {
    from {
        source-address {
            172.16.20.0/23;
            172.16.25.8/29;
        }
    }
    then settle for;
}
time period deny-rfc1918 {
    filter deny-rfc1918;
}
time period accept-the-rest {
    then {
        policer 80m-30.6m-discard-specific;
        settle for;
    }
}
[show firewall policer 80m-30.6m-discard-specific]
filter-specific;
if-exceeding {
    bandwidth-limit 80m;
    burst-size-limit 30720000;
}
then discard;

I suppose that is occurring due to existance of the service-set on the identical logical interface. Is there any approach to make this work ? Might this be a JunOS bug (sadly, this unit has to possibility of aquiring a help contract from Juniper Networks) ?

This unit is working the next JunOS model:

run present system software program
Info for jbase:

Remark:
JUNOS Base OS Software program Suite [21.2R3-S5.4]

Info for jcrypto:

Remark:
JUNOS Crypto Software program Suite [21.2R3-S5.4]

Info for jcrypto-dp-support:

Remark:
JUNOS DP Crypto Software program Software program Suite [21.2R3-S5.4]

Info for jdocs:

Remark:
JUNOS On-line Documentation [21.2R3-S5.4]

Info for jkernel:

Remark:
JUNOS Kernel Software program Suite [21.2R3-S5.4]

Info for jmacsec:

Remark:
JUNOS Macsec Software program Suite [21.2R3-S5.4]

Info for jpfe:

Remark:
JUNOS Packet Forwarding Engine Help (MX80) [21.2R3-S5.4]

Info for jroute:

Remark:
JUNOS Routing Software program Suite [21.2R3-S5.4]

Info for jsd:

Remark:
JUNOS jsd [powerpc-21.2R3-S5.4-jet-1]

Info for jsdn-powerpc:

Remark:
JUNOS SDN Software program Suite [21.2R3-S5.4]

Info for jservices-alg:

Remark:
JUNOS Companies Utility Stage Gateways [21.2R3-S5.4]

Info for jservices-cos:

Remark:
JUNOS Companies COS [21.2R3-S5.4]

Info for jservices-cpcd:

Remark:
JUNOS Companies Captive Portal and Content material Supply Container bundle [21.2R3-S5.4]

Info for jservices-crypto-base:

Remark:
JUNOS Companies Crypto [21.2R3-S5.4]

Info for jservices-ipsec:

Remark:
JUNOS Companies IPSec [21.2R3-S5.4]

Info for jservices-jflow:

Remark:
JUNOS Companies Jflow Container bundle [21.2R3-S5.4]

Info for jservices-nat:

Remark:
JUNOS Companies NAT [21.2R3-S5.4]

Info for jservices-rpm:

Remark:
JUNOS Companies RPM [21.2R3-S5.4]

Info for jservices-rtcom:

Remark:
JUNOS Companies RTCOM [21.2R3-S5.4]

Info for jservices-sfw:

Remark:
JUNOS Companies Stateful Firewall [21.2R3-S5.4]

Info for jservices-softwire:

Remark:
JUNOS Companies SOFTWIRE [21.2R3-S5.4]

Info for jservices-ssl:

Remark:
JUNOS Companies SSL [21.2R3-S5.4]

Info for jservices-tcp-log:

Remark:
JUNOS Companies TCP-LOG [21.2R3-S5.4]

Info for junos:

Remark:
JUNOS Base OS boot [21.2R3-S5.4]

Info for py-base-powerpc:

Remark:
JUNOS py-base-powerpc [21.2R3-S5.4]

Info for py-extensions-powerpc:

Remark:
JUNOS py-extensions-powerpc [21.2R3-S5.4]

dnat – Juniper MX and vacation spot/portforwarding NAT


I am struggling to get portforwarding engaged on a Juniper MX:

[show interfaces ge-1/0/0 unit 13]
description "CCTV and Entry Management";
vlan-id 13;
household inet {
    filter {
        output cctv-and-access-control;
    }
    service {
        enter {
            service-set nat-lan;
        }
        output {
            service-set nat-lan-portforward service-filter nat-lan-filter;
            service-set nat-lan;
        }
    }
    handle 172.16.20.1/24 {
        major;
    }
    handle 172.16.21.1/24;
}
[show services service-set nat-lan-portforward]
nat-rules sk7-port-forwarding;
interface-service {
    service-interface ms-0/2/0;
}
[show services nat]
pool prospects {
    address-range low 91.196.137.4 excessive 91.196.137.6;
    port {
        automated;
    }
}
pool sk7 {
    handle 91.196.137.254/32;
    port {
        automated;
    }
}
pool infrastructure {
    handle 91.196.137.253/32;
    port {
        automated;
    }
}
pool sk7-portforwarded {
    handle 91.196.137.252/32;
}
rule default {
    match-direction enter;
    time period no-nat {
        from {
            destination-address {
                10.0.0.0/8;
                172.16.0.0/12;
                192.168.0.0/16;
            }
        }
        then {
            no-translation;
        }
    }
    time period prospects {
        from {
            source-address {
                10.20.100.0/22;
            }
        }
        then {
            translated {
                source-pool prospects;
                translation-type {
                    napt-44;
                }
            }
        }
    }
    time period infrastructure {
        from {
            source-address {
                10.10.10.0/24;
                10.10.12.0/24;
                10.10.16.0/21;
            }
        }
        then {
            translated {
                source-pool infrastructure;
                translation-type {
                    napt-44;
                }
            }
        }
    }
    time period sk7 {
        from {
            source-address {
                172.16.25.8/29;
            }
        }
        then {
            translated {
                source-pool sk7;
                translation-type {
                    napt-44;
                }
            }
        }
    }
}
rule sk7-port-forwarding {
    match-direction output;
    time period default {
        from {
            destination-address {
                91.196.137.252/32;
            }
            destination-port {
                vary low 7000 excessive 7000;
            }
        }
        then {
            translated {
                destination-prefix 172.16.21.3/32;
                translation-type {
                    dnat-44;
                }
            }
        }
    }
}
[show firewall]
household inet {
    service-filter nat-lan-filter {
        time period skip-translation {
            from {
                source-address {
                    10.0.0.0/8;
                    172.16.0.0/12;
                    192.168.0.0/16;
                }
            }
            then skip;
        }
        time period default {
            then service;
        }
    }
}

pnat does work, so the hosts have entry to the Web, however portforwarding of tcp/7000 doesn’t:

[from MX itself]
emz@perm-mx5# run telnet 172.16.21.3 port 7000
Attempting 172.16.21.3...
Linked to 172.16.21.3.
Escape character is '^]'.
�^]
telnet> Connection closed.
[edit]

[from a host in WAN]
$ telnet 91.196.137.252 7000
Attempting 91.196.137.252...
telnet: Unable to connect with distant host: Connection timed out

This unit is operating the next JunOS model:

run present system software program
Info for jbase:

Remark:
JUNOS Base OS Software program Suite [21.2R3-S5.4]

Info for jcrypto:

Remark:
JUNOS Crypto Software program Suite [21.2R3-S5.4]

Info for jcrypto-dp-support:

Remark:
JUNOS DP Crypto Software program Software program Suite [21.2R3-S5.4]

Info for jdocs:

Remark:
JUNOS On-line Documentation [21.2R3-S5.4]

Info for jkernel:

Remark:
JUNOS Kernel Software program Suite [21.2R3-S5.4]

Info for jmacsec:

Remark:
JUNOS Macsec Software program Suite [21.2R3-S5.4]

Info for jpfe:

Remark:
JUNOS Packet Forwarding Engine Assist (MX80) [21.2R3-S5.4]

Info for jroute:

Remark:
JUNOS Routing Software program Suite [21.2R3-S5.4]

Info for jsd:

Remark:
JUNOS jsd [powerpc-21.2R3-S5.4-jet-1]

Info for jsdn-powerpc:

Remark:
JUNOS SDN Software program Suite [21.2R3-S5.4]

Info for jservices-alg:

Remark:
JUNOS Providers Software Degree Gateways [21.2R3-S5.4]

Info for jservices-cos:

Remark:
JUNOS Providers COS [21.2R3-S5.4]

Info for jservices-cpcd:

Remark:
JUNOS Providers Captive Portal and Content material Supply Container bundle [21.2R3-S5.4]

Info for jservices-crypto-base:

Remark:
JUNOS Providers Crypto [21.2R3-S5.4]

Info for jservices-ipsec:

Remark:
JUNOS Providers IPSec [21.2R3-S5.4]

Info for jservices-jflow:

Remark:
JUNOS Providers Jflow Container bundle [21.2R3-S5.4]

Info for jservices-nat:

Remark:
JUNOS Providers NAT [21.2R3-S5.4]

Info for jservices-rpm:

Remark:
JUNOS Providers RPM [21.2R3-S5.4]

Info for jservices-rtcom:

Remark:
JUNOS Providers RTCOM [21.2R3-S5.4]

Info for jservices-sfw:

Remark:
JUNOS Providers Stateful Firewall [21.2R3-S5.4]

Info for jservices-softwire:

Remark:
JUNOS Providers SOFTWIRE [21.2R3-S5.4]

Info for jservices-ssl:

Remark:
JUNOS Providers SSL [21.2R3-S5.4]

Info for jservices-tcp-log:

Remark:
JUNOS Providers TCP-LOG [21.2R3-S5.4]

Info for junos:

Remark:
JUNOS Base OS boot [21.2R3-S5.4]

Info for py-base-powerpc:

Remark:
JUNOS py-base-powerpc [21.2R3-S5.4]

Info for py-extensions-powerpc:

Remark:
JUNOS py-extensions-powerpc [21.2R3-S5.4]

linker – iOS archiving for launch strips away world symbols


I’ve a cocoapods library.

  • This library has some C features that I’ve uncovered globally:
#outline EXPORT __attribute__((visibility("default"), used, retain)) extern "C"

EXPORT void ios_prepare_request(const char *url) {
  // some obj-c code
}
  • Then internally a dylib is loaded. This dylib tries to name these features.
  • When run through Xcode, every part is working.
  • Nevertheless, after I package deal the app to TestFlight/Debugging deployment. There’s a stripping step that eliminates my world symbols. Due to this fact when I attempt to name any of the features from the dylib in some unspecified time in the future it will get a null pointer reference and the app crashes.
  • I have been making an attempt to get round this with the assistance of one of many apple engineers, his suggestion is to make use of a linker flag -export_symbols_list, however it doesn’t matter what I attempted it would not work.
  • I’ve managed to get it working by disabled world stripping within the consumer goal xcconfig, however this clearly shouldn’t be superb because it messes with the consumer goal.
  s.user_target_xcconfig = {
    'STRIP_STYLE' => 'non-global'
  }
  • By default cocoapods creates a static lib, so export_symbol_list will not work as it’s meant for dylibs, I attempted to resolve this by turning the lib right into a dynamic framework
s.static_framework = false
s.preserve_paths="exports.exp"
  s.pod_target_xcconfig= {
        # 'OTHER_LDFLAGS' => '$(inherited) -Wl,-exported_symbols_list,$(PODS_TARGET_SRCROOT)/exports.exp',
  }
  • With the default config an a static lib, claude suggests utilizing a -u flag and passing every image I have to hold alive, however this additionally doesn’t work
  s.user_target_xcconfig = {
    'OTHER_LDFLAGS' => '$(inherited) -Wl,-u,_ios_prepare_request'
  }

At this level I am out of concepts easy methods to stop the worldwide symbols from being stripped. In some unspecified time in the future I attempted passing the features in a initialization perform however in some way they had been nonetheless being stripped.

Any recommendations what may work?